This article is written from a Real World perspective.
Due to the many experimental processes used to make Tron, there are many visual mistakes (both visible and hard-to-spot), as well as audio and story errors. The following is a list of all of the errors found (as of 2008) in Tron.
In almost every shot of lightcycles, tanks and recognizers, there is some graphical error either with the shadows and/or the glowing outlines of the objects in the shot. Shots with Sark's Carrier, the Solar Sailer or the MCP have less graphical glitches, but there are several shot in the movie where there are exceptions.
In the lightcycle sequence where Kevin Flynn is racing through the maze, the second to last turn he makes has two frames where the color is separated.
One of many examples of shadow glitches.
As the Tron, Ram and Flynn escape from the Game Grid, for a frame, Flynn's lightcycle drives through a wall.
As Tron's lightcycle flies through the air after the tanks destroy the bridge, the solid shapes that makes up the "spokes" and the inner spheres of the front wheel is sticking completely outside of the bike.
Near the end of the movie when Tron looks over the edge of Sark's Carrier to see the ground, the CGI shot of Tron's Point-of-View looks as almost as if it was recorded directly off of a television. The landscape that moves by is covered in wireframe and the segment of Sark's Carrier that can be seen near the bottom of the shot is transparent.
A lot of shots from Triple-I feature this "ghosting" effect, where the wireframe can be seen through other objects. The wireframe for Sark's Carrier can be seen through this digital rock formation. However, the wireframe is very faint.
Yet another example of the ghosting effect. The Solar Sailer and the interior of the tunnel can be seen through the wall. The wireframe is very faint in this shot as well.
Computer World Continuity
Every shot in the computer world was hand-painted and animated with special effects using many, many layers. Due to the experimental process to bring these scenes to the movie screen, there are many error and continuity mistakes in effects, backgrounds, and so forth.
Since the glowing circuitry effect was achieved by putting black circuitry lines on a white costume and later matting them out to let the colored light shine through, anything else black (such as shadows) would have also been matted, thus explaining why Tron's circuitry has disappeared on the lower half of his body in this picture.
In the scene when Sark introduces himself to the new batch of programs held captive, the circuitry glows in one shot and several shots later, the circuitry is not matted and the original black circuitry lines can be seen.
Just as the Tron's lightcycle rezzes in, in the beginning of the lightcycle sequence, the bottom of his legs are missing. This is due to the lightcycle prop being in the way.
In some shots of the movie, props that are black can be seen through, due to matting out the black circuitry lines on the costume. In this case, the control grips of the recognizer are invisible.
A weird red glow effect briefly appears behind the guards, shortly after Flynn rezzes into the computer world.
Another example of black objects being matted out. In this shot, it is a part of Sark's headpiece that is being matted out.
