Walt undergoes tests to see if his cancer treatment has reduced the size of his tumor. Dr. Delcavoli won't share the results for another four days, but upon briefly glimpsing the scan’s image, Walt notices a large white spot on top of his lung.
Saul gives Walt a tutorial on money laundering. After all the costs associated with Badger’s arrest, Walt has $16,000 left, of which he would receive only $9,960. Walt lets on that he might not have much longer to live, but intends to cook a lot more. Elsewhere, Skyler suggests a weekend outing to take the family's mind off the test results, but Walt says that he wants to visit his mother to ensure she'll leave money to Skyler if he dies.
Jesse makes plans with Jane to visit the Georgia O'Keeffe Museum in Santa Fe, but Walt derails the getaway when he tells Jesse that they need to cook non-stop until Tuesday. When Jesse balks, Walt tells him that their methylamine is losing its chemical potency.
Skyler drops Walt off at the airport and drives away. After a moment, Walt exits the airport and Jesse pulls up in the RV to take Walt to their cook session. They drive deep into the desert and prepare for a long cook. When Walt scolds Jesse for tossing the RV's keys on their workspace, Jesse leaves the keys in the ignition. Unbeknownst to the duo, an indicator lamp on the dashboard lights up.
Walt and Jesse are ecstatic when two days of cooking yields 42 pounds of meth, which will net them $672,000 each. However, their celebration is cut short when they realize that their generator has run out of gas, Jesse is concerned, but Walt insists that they keep cooking until they've exhausted the methylamine.
Jesse suggests they break for the night: a trip to Denny's, a hot shower, and a bed instead of a cot are too good to pass up, he argues. Walt finally agrees, but they discover that because Jesse left the keys in the ignition, the dashboard indicator lamp has completely drained the RV's battery. Walt fumes at Jesse now that they are now stranded in the desert.
Walt siphons some gas from the RV and rigs the generator to jump-start the battery, but Jesse spills gas all over the generator. A subsequent spark sets the generator ablaze. Just as Walt arrives with a fire extinguisher, Jesse douses the flames with their remaining drinking water. "Excuse me for thinking on my feet," Jesse says when Walt blames him for their predicament.
Jesse tries to call Skinny Pete for help, but can't get a cell phone signal. Walt's phone works, but he assumes that Skyler checks his call logs and only reluctantly hands it over to Jesse. Skinny Pete gets lost on the way, and Walt's phone's battery dies before Jesse can redirect him. The next morning, Walt tries to "trickle charge" the battery by hand-cranking the generator. He and Jesse share cranking duties for hours in the hot sun. Taking a break, Jesse walks over to Walt, who erupts into a heavy fit of coughing. Jesse realizes that Walter's health must be eroding and that he lied about the methylamine spoiling.
After still more cranking, the engine fires up briefly, but dies. Jesse punches the dash in frustration. He exits the RV to find Walt sitting in a field of grass, one palm covered in coughed-up blood.
Resigned, Walt and Jesse lay on cots in the RV to escape the desert heat. "I deserve this," Walt says. Jesse argues that everything Walt has done was for his family. Walt counters the only thing he ever did for his family was worry and disappoint them. "All the lies," Walt continues. "I can't even keep them straight in my head anymore." Jesse wants to start walking out of the desert, but Walt warns that he'll die within an hour.
Jesse rattles off things Walt could create with their lab supplies — a robot, a homing device, a dune buggy — until one idea clicks with Walt: he can make a mercury battery using chemicals, coins, and galvanized metal. Explaining the science to Jesse as he goes along, Walt assembles the battery. The duo connect the battery to the RV and a big spark shoots off the terminal. Back in the RV, Walt tries the ignition and after several anxious seconds the engine groans to life. When Jesse drops off Walt at the airport, he assures him that, "Whatever happens, your family will get your share," Jesse replies.
At Dr. Delcavoli's office, Walt learns that, contrary to his worst fears, his cancer is in remission and his tumor has shrunk by 80 percent. Skyler, Junior, Hank, and Marie celebrate, but Walt admits he has been coughing up blood, to which Dr. Delcavoli reveals that the large white spot on his scan is treatable tissue inflammation. Walt goes to the restroom and washes his face. As he dries his hands, Walt looks up and sees his reflection in the metal towel dispenser. After pausing briefly, Walt violently punches the dispenser with his fist in anger.
- The title is a reference to the length of time Walt had to wait for his test results, as well as how long he was stranded out in the desert with Jesse.
- The teaser was shot the front lobby of the Breaking Bad production office at Albuquerque Studios. The bathroom in the following scene is also the real bathroom just down the hall from the production office.
- The plot of the episode is a homage to "The Flight of the Phoenix" the 1965 film about a plane crash that leaves its passengers stranded in the desert
- The footage of Jesse driving the RV onto the highway was filmed when Aaron Paul accidentally missed a turn, and entered an on-ramp. There was no intention to actually put such an unstable vehicle on the open road, but the cameras kept rolling and Aaron Paul managed to never break character as he tried to get back on track.
- Depending on the scene and direction of the camera, the intern of the RV had to be shot in two parts - either inside the actual vehicle in the desert or in the RV set on stage.
- The shot of Bryan Cranston and Aaron Paul urinating wasn't in the script, but Michelle MacLaren really wanted to do. Cranston and Paul were ready early on the first day of shooting, so the crew was able to steal the shot right at sunrise before the starting of the day's work.
- The Breaking Bad team took a little bit of artistic license with the battery storeline in this episode. It's not possible to trickle-charge an RV battery in this fashion
- It was Bryan Cranston's idea for Walt and Jesse to use the lawn chairs for shade
- Barely visible, there is a trained tarantula crawling right by Walt's arm in one scene. The scene originally had footage of the tarantula crawling down his arm, but was cut for time. In an episode of Malcolm in the Middle, Cranston had to let a tarantula crawl over his face
- Vince Gilligan's favorite line of the episode was unscripted: "...a robot?" The line was pitched by the show's 1st AC, Nick Shuster.
- Cranston could not punch the location's real paper towel dispenser, because it was incredibly hard and would've broken his hand. Instead the art department put up a fake dispenser of more malleable material for him to strike.
- At the beginning of the episode, Saul Goodman suggests that Walt is aspiring to become a Vito Corleone-style figure in the underworld, but then suggests instead that he's more akin to Fredo Corleone; Vito's hapless son. At the end of the episode, when Walt receives his test results, Hank inadvertently implies that he is in fact Michael Corleone, by quoting a famous line from The Godfather Part III; "Just when I thought I was out... they pull me back in!"
- Although Walt criticises Jesse by saying masturbating doesn't constitute a real weekend plan, in the Pilot (2005 script), Walt himself masturbates in the morning out of boredom.
- The flashback scene between Walt and Jesse in El Camino takes place in between the RV being jump-started and Jesse dropping Walt back off at the airport.
- "Good Morning Freedom" by Blue Mink (during the driving montage)
- "One By One" by The Black Seeds (during the cooking montage and over the end credits)
- "Three Days Out" by Dave Porter (when Jesse finds Walt coughing up blood and as he tries to trickle charge the generator)
- "Sitting around, smoking marijuana, eating Cheetos and masturbating do not constitute plans."
- ―Walter on Jesse's plans for the day.
- Walter: "I have it coming. I deserve this."
- Jesse: "Snap out of it. First off–everything you did, you did for your family. Right?"
- Walter: "All I ever managed to do was worry and disappoint them and lie. God. All the lies. I can’t even–I can’t even–keep them straight in my head anymore."
- ―Walter and Jesse in the RV
- "What? Come on! Man, you're smart. You made poison out of beans, yo. Look, we got, we got an entire lab right here. Alright? How about you pick some of these chemicals and mix up some rocket fuel? That way you could just send up a signal flare. Or you make some kind of robot to get us help, or a homing device, or build a new battery, or... Wait. No. What if we just take some stuff off of the RV and build it into something completely different? You know, like a... Like a dune buggy. That way, we can just dune buggy or... What? Hey? What is it? What?"
- ―Jesse attempting to motivate Walt.
- Walter: "Good. And now, what shall we use to conduct this beautiful current with? What element?"
- Jesse: "Wire!"
- Walter: "Copper"
- ―Jesse showing his enthusiasm but lack of scientific knowledge while trying to solve their battery issue
- Trivia Compilation - "4 Days Out" S2 E9 - Breaking Bad Official YouTube channel