Audio problem: When the woman at the metal detector says to the man with the metal arm and leg "Would you put all your metals objects into this dish please", her mouth doesn't move for the second half of the sentence. (00:03:00)
Audio problem: When the girl scouts are fighting and one of them slides the other one across the table and she hits the jukebox, you hear a shattering sound, but it doesn't shatter. (00:16:25)
Audio problem: Most of the time when everyone is getting beat up by Kramer on his way to the airport, not many people move their mouths when they talk. (00:54:40)
Audio problem: In the first scene where Ted and Elaine meet in the airport you can see that they have dubbed their voices in the edit.
Answer: This is a reference to The Godfather, where a character being intimidated by the Mafia wakes up with his prize racehorse's severed head next to him on the bed. For comedy purposes this is twisted by the movie as an implied sexual relationship, when the horse is revealed to be alive.