Continuity mistake: Kramer is holding his hands in front of him with a back scratcher in his left hand, and then suddenly after a cut his hands are not up and we don't see him holding a back scratcher. He proceeds to close the door with his left hand, which is now holding nothing. (00:05:25)
Audio problem: When George says "and it will be easy because the receipt is in my good friend," the S in the word "because" is partially cut off at the end, indicating two different recordings were edited together. (00:18:35)
Continuity mistake: When George is about to walk away from Jerry, he begins to close up his wallet, but in the next shot, it is fully open again. (00:18:40)
Continuity mistake: When Newman and the landlord look into Kramer's apartment through his peephole, the background doesn't match from when they look in and when he opens the door.
The Cartoon - S9-E13
Continuity mistake: After George and Janet leave The Apartment, Jerry gets mad at Kramer for saying Janet looked like him. He shoves Kramer and the bottom half of the freezer door swings open. The next few shots show Jerry and Kramer from the chest up, but when a wide view shot is shown again, the freezer door is closed. It does not appear Jerry shut the door.
Plot hole: When Elaine meets Glenn's welfare case worker at The Apartment, the case worker does not tell Elaine that Glenn actually has a wife (after clarifying that she isn't The Wife). This is pure plot convenience. When Glenn's wife finds Elaine in The Apartment, he says "You're home early." She lives there, they are not separated, and surely the case worker would be involved with both of them, not just Glenn.
Continuity mistake: When Loretta comes into The Apartment she is carrying a coat and roses in one hand and the other hand is supporting her handbag by her right shoulder (left on screen). In the next shot she is holding the bottom of the flowers with both hands instead of just the left hand.
Continuity mistake: When Kramer and Jerry are talking about the bird being in the hallway, notice how the intercom keeps changing. In some shots the intercom is not set straight and leaning to the right and in other shots it is completely straight. The most notable change is when Kramer is leaving The Apartment. It goes from crooked as he is leaving, then straight while he is outside in the hall and then the entire unit is completely pulled right out after Kramer rushes backs in.
The Burning - S9-E16
Continuity mistake: At the beginning of the episode, when Puddy is farewelling Elaine on the street, he is standing on the sidewalk and leaning through the driver's window. The following shot when she pulls out quickly, you can see through the windows of the car that Puddy is nowhere to be seen.
Factual error: When Peterman is making a toast at his party, he quotes what he says is something said by the Papa New Guineans, and he proceeds to pronounce a sentence filled with clicks (lingual-ingressive consonants). However, this is impossible, as clicks are only used in southern African languages and three east African languages. (00:03:10)
Revealing mistake: When Kramer at the start of the episode puts the hose on the kitchen tap, he jerks the hose as it's not long enough to reach The Fire. If you look at the sink when Kramer does this, it comes easily out of its position on the counter top.
The Frogger - S9-E18
Factual error: Frogger machines kept scores, but they didn't keep the initials of the person who got the score.
Visible crew/equipment: After Elaine gets out of the taxi, she starts walking on the sidewalk, before chasing after the taxi once it drives away. The reflection of the filming crew can be seen in the windows of the buildings next to her when she starts walking. (00:06:32)
Continuity mistake: The private jet that The Limo pulls up to on the ground and the one that they show the gang on while flying are two different types of planes.
Factual error: At several points during the case, the prosecutor introduces witnesses by saying "The state calls." Legally, Massachusetts is a Commonwealth, not a state, and that is how it is referred to in court. (See any episode of "Ally McBeal" or "The Practice.") However, even this would be incorrect here, as the episode makes it clear that the "Good Samaritan" law is a local Latham statute, not a Massachusetts law. In this case, "The people call." would be correct.
Factual error: Elaine is placed in the same jail cell as the others. No police department anywhere in the U.S. would put a woman in the same cell as men.
Answer: The name is Delores. He shouts that name at the end of the episode. Then in a later episode, "The Foundation", he runs into her. And he repeatedly calls her Delores.