Upstairs Downstairs Downstairs - S5-E1
Visible crew/equipment: Shadows from the booms are quite visible in varied takes, along with false ceiling in the living area of their apartment.
Revealing mistake: Studio lighting on Janet and Chrissy's tent at night, in the middle of the woods. (00:21:12)
Visible crew/equipment: A large shadow of a crewman's shoulder is visible on the wall behind Larry after Janet exits to the kitchen. (00:16:37)
Days of Beer and Weeds - S2-E22
Visible crew/equipment: Reflections of the monitors and other equipment are visible in Janet's glasses at the end.
The Case of the Missing Blonde - S5-E21
Plot hole: After being stuck inside the phone booth, the police officer arrests Larry for vandalism after Larry breaks the glass in the phone booth. In a real-world situation, an officer would most likely let someone go without arrest if the person got stuck inside like that (declaring an emergency) and couldn't get out without breaking the glass.
Helen's Job - S2-E13
Factual error: After Mr. Roper stirs Jack's batter, Jack pours it into the cake pan and then opens the oven, leaving plenty of batter residue inside the mixing bowl, which a professional chef student would never do.
Factual error: Jack takes Cheryl's phone off the hook and puts it down, but while the two are talking throughout the two-minute scene, the phone does not make the loud annoying buzzes that occur after 30 seconds or so from the phone being off the hook (which happened back in the years the show aired).
Jack Goes to the Dentist - S7-E2
Character mistake: Terri's boyfriend, a dentist, says he took the Hippocratic Oath then corrects himself saying it's only for doctors. Dentists also do take the Hippocratic Oath.
Revealing mistake: After Chrissy purposely spills the wine onto her married date's lap, he raises the glass, and it's cleverly covered in saran wrap, so that the glass pieces don't go flying when she breaks it with hers.
Character mistake: When Felipe thinks Jack proposed to his cousin Maria, Felipe is happy and congratulates Jack. Later in the episode though, Maria's fiancé shows up and Felipe is shown as already knowing about him. Why wouldn't Felipe tell Jack that Maria was already engaged instead of showing happiness of Jack's "proposal"?
Suggested correction: You missed the entire plot of the episode. Maria's fiancé broke off the engagement, so she went to Felipe's. Then, when he thought Jack had proposed, he was happy. But Jack thought he was happy for offering her a job. Jack then begins talking about Maria as an employee (like trying her out in the kitchen and getting someone to train her). But Felipe thought Jack meant those things about Maria being his wife and got mad at Jack. Then told Jack he's not marrying Maria.
Plot hole: How could a blind man (Jim Walsh) just find Jack's apartment like that? Phoning from the Reagle Beagle, Chrissy simply states "you're nearby to us" and then hangs up the phone (without giving the address). Even if he was given the address, being blind he would not be able to find the building, let alone the right unit that quickly, but he knocks on the door within 5 min of the call.
Visible crew/equipment: Obvious shadows from booms, overhead, and crew members reflect off the walls while Jack and Larry are talking, and Larry looks like he's either reading from cue cards or following an off-camera director for his blocking moves.
Jack in the Flower Shop - S2-E19
Other mistake: John is wearing a dental retainer during the closeups of Jack talking on the couch with Chrissy.
Character mistake: When Jack is tending bar, the one woman states margaritas don't include tequila, when it's the primary liquor.
Suggested correction: This is from s02e10, "Stanley Casanova." However, she doesn't say margarita, she says daiquiri, which is what Jack made with tequila. Daiquiris don't contain tequila but typically rum.
Revealing mistake: Any time a main house light or a lamp is switched off, it is still bright from the studio lights.
The Not-So-Great Imposter - S5-E9
Plot hole: All these characters (the bookie, policemen, the sister, the husband) were after David Miller and all come to attack Jack in some way (thinking Jack is David Miller). However, a big city like LA most likely has several David Millers so why would they all assume this David Miller is the one they're looking for? So even though Jack's name could have been David Miller, how would everyone think he is the one they're looking for?
Suggested correction: These are questions, not plot holes. First, Jack and the restaurant are in Santa Monica, not LA. At the time, Santa Monica had a population of around 88,000. While the article was printed in the LA Times, there wouldn't be a lot of famous, professional chefs, working/living in Santa Monica named David Miller.
Continuity mistake: In the very first episode, there is a silver light fixture hanging from the ceiling in front of the kitchen. The light fixture appears and disappears throughout the first season.
Factual error: In this episode, Jack asks Felipe how he can bring Mr. Angelino to The Apartment, in which he answers "We took the Santa Monica freeway to the Cloverfield exit." The Cloverfield exit is in reality, a good 2 miles or so from the beach (2 other exits are much closer to beach than this). Yet throughout the series, it is implied that The Apartment is very close to the beach (3 blocks is stated by Jack in a much earlier episode). Why a far exit for a beach-area apartment?
Suggested correction: Correcting my own entry: I just recently saw this episode for the first time in a long time. Felipe actually says the "Centinela" exit (not "Cloverfield"). Technically this even adds to the mistake as it is one exit even FURTHER from the beach area apartment. Now 3 miles away exiting (instead of 2 as previously submitted).
Revealing mistake: When Chloe (the new hire) and Janet are talking on the couch near the end, water spots suddenly appear on Chloe's shirt, indicating the actress was lactating while filming.
Suggested correction: Just because it was never mentioned in the storyline of the show, there is no reason Chloe couldn't have a baby at home thus causing the lactating.
Sorry, but the wording in this correction is confusing. Agreed, there was no mention in the show of Chloe having any baby at home. So very well, she may have been lactating, which explains the sudden water spots as mentioned.