The Calzone - S7-E20
Continuity mistake: This mistake is in The Calzone episode. Towards the end when George walks in and his boss is looking around for the smell of calzones, George is holding a bag in his hand. In the next shot that shows the back of the boss's head the bag is now on top of a box that George is carrying. When it goes back to a close up the bag is in his hand again.
Continuity mistake: When Elaine crushes the beer can in Jerry's apartment, she leaves it on the counter. After she walks out of The Apartment, the beer can is on the cutting board.
Continuity mistake: The scene which George arrives at Beth's apartment in a messy condition to admit his remark was in jest, his shirt's hem and collar change between shots. During this scene, especially when he talks to Jerry on the phone, his collar is up and down; his hem is in and out of his trousers.
Continuity mistake: When George and Susan are arguing over dinner about her cousin stealing the name Seven, Susan holds her glass up to her mouth in one shot. In the very next shot, the glass is on the table.
Continuity mistake: When George is at Susan's cousins' house complaining about them stealing the name Seven, its bright Daylight out. You can tell because the sun is pouring in through the windows. The woman goes into labor and they all get into the car to go to the hospital. At this point it is nighttime. When they finally arrive at the hospital it is broad daylight again.
Continuity mistake: When Jerry and Elaine are talking in The Apartment, after George and Kramer go see the horse, the G+W Motorwerkes magnet disappears from the fridge.
Continuity mistake: In the start of the scene when Kramer tells Elaine that the armoire got stolen. When Elaine walks in from the right side she walks right past the armoire, and it still has the two blue straps on it so it's the same one. The gaffe seems to have been edited out in some versions. (00:09:50)
Continuity mistake: When Jerry finds The Soup Nazi's recipes in the armoire he hands Elaine at most 4 pieces of paper, but when the shot changes to Elaine the number of recipes in her hands has increased dramatically.
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.