20 Things You Somehow Missed In Friday The 13th (1980)
14. Bill's Twitching Eye
Bill Brown (Bing Crosby's son, Harry) suffers another of the film's most shocking deaths, not least because it takes place offscreen and the audience only realises it at the same time as Alice does.
Leaving the camp's generator cabin, Alice finds Bill pinned to the door by several arrows that have gone right through his body (the killer in the original film has quite a thing for archery, but also appears to have slit Bill's throat just to make sure). One of these arrows has gone right through Bill's head, having been shot through his left eye.
However, if viewers watch the scene in which Bill's body is discovered carefully, they can see that Bill's left eye is twitching slightly. This is because Harry Crosby found that Tom Savini's make-up for Bill's death scene was very irritable, to the point where his left eye was literally in agony during the filming of this scene.