Other mistake: When Mr. Bavalaqua is telling Jerry and Duncan the rules for the big race, there is a male extra right behind him who is mouthing Bavalaqua's lines as he's talking. (00:21:00 - 00:22:00)
Continuity mistake: In the episode with Bette Midler, she is injured when George tackles her at home plate. When he hits her, she is knocked into somebody. When they show her again, she is sprawled against the backstop with no one behind or even near her that seems to be hurt. George also misses home plate.
The Doodle - S6-E20
Continuity mistake: In this episode, Newman's apartment number is 5F but in all the episodes both before and after, The Apartment number is 5E.
Continuity mistake: Right after Jon Voight enters the taxi, Kramer sticks his arm in through the cab's rear side window, where Jon Voight was sitting. Jon Voight grabs the arm and bites Kramer on the wrist. As Kramer later was describing the incident to Jerry and George, he was pointing to a bite mark near his elbow.
Factual error: The Devils-Rangers game is at Madison Square Garden, but when the Devils score, a siren goes off. That would only occur in the event of a Rangers goal.
Factual error: In this episode, after accepting a free Armani suit from Kenny Bania, Bania insists that Jerry repay him by taking him to a nice restaurant. Jerry takes Bania to Mendy's, a Glatt kosher NYC deli. During the ordering process Bania suggests, "Oh, get the swordfish. Best swordfish in the city. The best, Jerry." Swordfish is considered an unkosher fish by Glatt kosher standards since it does not have scales, one of the essential criteria. It would therefore never be served at Mendy's.
Visible crew/equipment: In the final scene with Larry David guiding Noreen off the bridge, a crew member's arm is visible in the bottom right corner of the screen. (00:22:30)
Visible crew/equipment: When George and Elaine are in the cab, you can see the studio lights reflected in George's and the cab driver's glasses.
Character mistake: When Jerry is being questioned on the lie detector test about "Melrose Place", the officer questioning him asks him two control questions that he responds to in full sentences. The questions should have been simple "yes" and "no" questions.
The Gymnast - S6-E6
Continuity mistake: When George is at his girlfriend's mother's house, the plates on the table switch around. Then the order he stacks them changes. When he picks them up, the plate with the chicken is in the middle with a plate with a napkin on top, then in the kitchen, the plate with the chicken is on top.
Character mistake: George makes a big deal about wanting to say "I love you" to the girl he's dating and says he's never said it to a girl, just a dog once, and he wants to say it just once. But in s02e01, "The Ex-Girlfriend", George tells Jerry he had to say "I love you" to Marlene when she told him she loves him.
Continuity mistake: Kramer takes an awkward Polaroid of Jerry for his wall, but the photo on display is an ordinary print. (00:09:45 - 00:12:00)
Continuity mistake: When Elaine gets kicked out of the nail salon it is a clear day (in fact the whole episode is) then the next scene she meets J Peterman at night and in the rain. When she left the salon she is wearing a red blouse, no jacket. When she meets Peterman she is in a trench coat with a white blouse. The Peterman portion of this episode really makes no sense.
Chosen answer: George does mention his brother in the episode "The Parking Space". They actually really never mention anything that contradicts the fact he had a brother though, it just isn't mentioned.