I saw a show the other night called Movies Greatest Mistakes: Part 2, in which the host (Robert Webb) guides us through some of the greatest mistakes and bloopers from a wide range of great and classic films, including The Godfather, Transformers, X-Men, Star Trek, etc.
And they did a segment on Tron Legacy (which he jokingly referred to has 'dreary').
There were four mistakes that he highlighted, and they are:
(1) When we see Sam on his bike in the tunnel, he's swerving through the cars. Just above them on the tunnel roof we see some road signs with a big 'X' illuminated on them-thus showing that the tunnel is in fact closed (or the cars are going the wrong way-I cant remember which exactly).
(2) When Sam gets his parachute caught on the street lamp outside the Encom building, he frees it and lands on top a taxi, which swerves to shake him off.
The camera changes angle to show the road ahead, and in the distance we see some police cars enter the street and drive towards them.
And yet, when we see the road ahead again a few moments later, we see the same police cars enter the road again.
The editors appear to have used the same footage twice.
(3) After the Solar Sailor lands on board the Rectifier, Quorra gives Flynn her Disk, says "Goodbye" and runs off. Rinzler sees her, intercepts her and after a brief struggle leads her aware, with Flynn and Sam sneaking off behind them.
When Quorra fights Rinzler, the light strip on her legs is on one side of her body, and yet when we see Rinzler lead her away it's now on the other side-thus indicating that the scene has been flipped (or reversed).
(4) When Clu is giving his speech to the Sentries on board the Rectifier we see a close up of one of the Sentries and see a reflection of Clu in his visor (thus giving the impression that he is IN FRONT of him).
And yet in other scenes we see NO Sentries in front of him-there is just a open path between the formations of Sentries.
I apologize if these have already been mentioned before, but they were knew to me at the time.