Revealing mistake: During Jack's dance scene, the old lady that he dances with spins away from him and knocks off a man's toupee. The actress was supposed to knock it off as she went by, but it's obvious that she misses and instead quickly reaches over to snatch it off his head instead.
Continuity mistake: In the scene where Jack, Janet and Terri are on the air for the cooking show, Janet holds up the silver bowl but there is no parsley in it. Then in the next shot the bowl is instantly full of parsley.
Gigolo Jack or Professor Jack - S6-E4
Continuity mistake: In the scene where Terri admits to Jack that she mistook his cooking lessons for lovemaking lessons, look at Terri's bangs. They go from on her forehead to brushed back then back to on her forehead then back to being brushed back.
Other mistake: In the Regal Beagle, Jack addresses Marsha as Ms. White although later in the episode her last name is revealed to be Whitewood. In addition, how could Jack have known her last name anyway? Marsha only said her first name in front of Furley and the trio early in the episode and presumably she hasn't talked to the trio since she left with Furley out the door.
Suggested correction: In addition to the other correction (occurring 00:07:25), this correction addresses the second part of the mistake, as to how Jack knew Marsha's last name. Earlier, when Larry tells the trio that Furley was fine with him being late with the rent, Janet states, "He's been wining and dining her for 3 days" (at 00:06:15). So at any time during those 3 days (offscreen), Furley told the kids about his dream girl, which would have included her last name.
Suggested correction: No Jack does say, "Hello Ms. Whitewood!" While they are shaking hands. Time stamp in the episode when this occurs is at 7:25.
Jack Bares All (a.k.a. Oh, Nurse) (2) - S6-E2
Continuity mistake: In the scene where Terry puts on the gag glasses, notice how the black circles under her eyes get larger after the shot changes.
Strangers in the Night - S6-E12
Character mistake: The whole idea of the serenading scene was Larry was supposed to hide and sing for Jack while Jack would be shown in the yard alone and pretend to be the one singing, but the yard was brightly lit and Larry was right behind Jack and both were very shown with nothing to hide Larry.
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).