In the very last scene, Phil Silvers does a karate chop on the cereal table at the weight contest. A split second before he "chops" the table, he turns his hand downward and instead slaps the table. They try to hide this with a cereal box, but you can still see the error.
At around 1h 20 min into the movie; during the parallel shot of Dexter driving and having a conversation with the police officer, a studio light can be seen reflecting off of the A-pillar window of the car.