In a lap dancing club Christopher is clearly seen with two topless dancers. When he gets a visit the dancers' tops both magically reappear momentarily before they become topless again at the end of the scene.
When Christopher is standing and showing off his scar, the camera angle changes and now he's sitting down with his shirt down.
Paulie says that "Allegra" (the name of the bride) means "happiness" in Italian. Even though, it means "happy" (feminine adjective) and "Happiness" is "allegria", his associates wouldn't know the difference because they're all not fluent in Italian anyway.
AJ's date to the wedding tells Tony she doesn't eat fish because of the toxins, yet she is seen smoking. That was the joke.