The laser fired by the M-66 unit changes color four times throughout the film: it is first red then green in the forest, blue in the city, yellow in the restaurant and then red for the rest of the film.
The repulsive effect between the "donut" device and the M-66 unit occasionally defy the laws of physics: Assuming that the "donut" is much lighter than the M-66 (which it probably is), the unsupported device should be repelled by the robot, not the other way around.
The skeleton of the destroyed M-66 unit has separate jaw, despite that character having a static face.
Sybil's name is consistently misspelled as "Shebel" on her shirt pocket.