Factual error: Under US law neither Peter Lowenstein nor Oscar Grace would be allowed any level of participation in the investigation, arrest and prosecution of Ned Racine. Both have a highly visible social relationship with him, which disqualifies them from having anything to do with a criminal case against him. In fact as soon as he became a suspect in Edmund Walker's murder they would both be officially 'warned off' - told not to contact him again for any reason.
Factual error: At the end of the film where the blinded Michael is swinging his scalpel aimlessly, it makes loud "swooshing" sounds. This is pure fantasy. I have personally mimicked what Michael did using similar small scalpels and even larger knives without almost no sound when swinging them.
Factual error: The wrestler is killed by Snake stabbing the back of his head with a spiked bat, having rather long and thick spikes on it. As the Wrestler falls against the net, the back of his head is shown as he is slumped over the net. There is no wound on his head, nor any trace of blood, despite having one or more large spikes just jammed into it. (01:16:55)
Factual error: The spotter pilot is Captain Tucker of the Royal Canadian Air Force. But the RCAF of the 1930s used RAF ranks. He would actually be a Flight Lieutenant.