Kevin Flynn sets down a metallic polyhedron on the fireplace mantle. Later, when CLU comes in his house, he picks up this same metallic polyhedron. This is a direct homage to TRON (1982) since this is a Bit which assisted both the original CLU and Flynn.
A notable absence in this sequel are the tanks, but you can still see a sort of cameo by one of them on the street below after Sam is first captured and a second time in the background when he returns to the city in the vintage light cycle.
During the motorcycle chase, the motorcycle officer uses radar on Sam speeding through the tunnel. The officer's radar indicates 86 mph for lock speed and 103 mph for patrol speed. Patrol speed would be the speed of the officer if he were moving but since he was stationary, his patrol speed would be zero mph.
Is Tron in this movie the original program from the first movie?
Yes. Flynn had the original Tron security program transferred to the new grid that he created.
Is the entire film in 3-D?
No, it is not, but that is due to the filmmaker's wishes. The "real world" footage is presented in 2-D, and the "Electronic world" footage is presented in 3-D, as per the filmmaker's intentions. A disclaimer clarifies this before the opening credits in the 3-D versions of the film and advises that the audience put on their 3-D glasses right then and there due to the Disney logo and the opening credits being presented in 3-D.
What does 'de-rez' mean?
It is short for de-resolution, the electronic equivalent of death. When a program in Tron de-rezzes, it ceases to exist.