Continuity mistake: The leather straps on Charley's legs on her bed keep loosening up between shots.
Continuity mistake: At the end of the show Damon throws his mic to the floor, and it cuts to a close-up of the mic breaking apart in to several pieces. In the next wide shot the mic is lying intact on the floor. (00:55:45)
Revealing mistake: Obviously not Jane Seymour sitting on the bed topless as her back suddenly looks tanned.
Deliberate mistake: After Ryan and Michelle finish changing the flat tire and are surprised by Leatherface, he chases Ryan around the back of the car and smashes the windshield. At the moment the camera is in the backseat shooting out, we see the chainsaw with the chain popped off and hanging. My best guess is that it was done intentionally (for safety reasons) because the saw was close to Ryan. The crew must've been too lazy to completely remove the chain and just popped it off the track instead. (00:25:25)
Continuity mistake: A helicopter drops two harnesses down to Chuck Norris (Major McCoy) who is awaiting with an unconscious bad guy, and tethers the villain to the ropes dropped by the hovering copter. The black harness ropes are shown dangling from the chopper throughout. When McCoy radios to "pull us up" with the villain in view, the once visible ropes are nowhere to be seen. (01:41:40 - 01:42:05)
Character mistake: G. Peppard holds up a Walther P-38 pistol and calls it a Walther PPK.
