Factual error: Admiral Motti tells General Tagge, "Dangerous to your star fleet, Commander," even though Tagge is an army general and could not command a star fleet.
Suggested correction: It's heartening to see how they adhered to human, earthly military conventions a long time ago in a galaxy far, far away.
Other mistake: After the tractor beam pulls the Millennium Falcon into the Death Star, there's a shot of a MSE-6 droid ("mouse droid") at the feet of four stormtroopers. The trooper in the back right, is holding onto his helmet in a desperate attempt to keep it from falling off. (01:03:15)
Suggested correction: The "desperate attempt to keep it from falling off" is a presumption. Yes, he's holding onto his helmet, but the scene only lasts about a second. There's not enough information given for the emotion of someone in a mask to be determined.