Thought about this recently, Tron Legacy would have been better with this change:
Switch the night club scene with the arena scene.
Basically, when Sam enters the rabbit hole, the first place he shows up is Castor's. Quorra ends up rescuing him from Castor's club, takes him to see Flynn.
Sam then goes to fight Clu and that's when the Recognizer captures him and puts him in the Arena.
From the Arena, thats were Flynn comes and rescues Sam (in his special lightcycle).
So basically we still get those 2 scenes, but they are switched. The reason for the change is that I don't think it made sense for Sam to be dropped into the arena on a whim of some random recognizer patrol. Clu should have been responsible for putting him on the arena. Also, I think the film sorta slowed down during the club scene. I think it would have been better to put that scene at the beginning so that the tension continually builds from the rabbit hole to the club scene to the arena to the final battle.