Factual errors: When young David shoots his brother there is no recoil of the gun. A small child should have felt the recoil very hard and moved his arm but in that scene the gun didn't move his arm at all thus proving it's not real. The same problem appears in the scene where David shoots Jane.
Factual errors: David's brother was killed shortly after the Vietnam war. That means that his body should have been in a high state of decomposition, but in the closing scene he appeared "fresh".
Continuity: In the flashback, the handgun David's brother loads and cocks is a Beretta. After young David comes back and gets the gun from the drawer it changes from a Beretta to a Colt.
Errors made by characters (possibly deliberate errors by the filmmakers): The talk show host Marty Clark says that David Murch's brother Phillip is buried in "Silver Springs, Maryland." Although commonly but mistakenly called "Silver Springs," the city is actually "Silver Spring."
Errors made by characters (possibly deliberate errors by the filmmakers): The first Marine to return from the dead tells the Air Force sentry, "At Ease, Soldier." Air Force personnel are properly addressed as "Airmen."
Factual errors: Philip Murch's tombstone lists his rank as Lance Corporal. When he returns from the dead, he showing wearing an Army uniform. Lance Corporal is strictly a rank in the Marine Corps.