In the 1974 horror film The Texas Chainsaw Massacre, there’s a scene during the third act where the character Sally gets kidnapped and treated to “dinner” with Leatherface and his family.
The scene, considered one of the scariest put to film, was just as much of a nightmare to actually make. The hot weather and filming lights made the food on the table rot quickly, resulting in a horrible stench that was made worse due to poor ventilation. Not only that, but the crew had been filming for 27 hours straight at that point, and it got so bad to the point that the actors had begun to legitimately go insane and think that they themselves were really the characters they were playing.
Edwin Neal, a recently-returned Vietnam veteran at the time and the actor who played the Hitchhiker, described the experience as worse than anything he went through in that war. Gunnar Hansen, the actor who played Leatherface, stated on the film’s DVD commentary that while filming that scene, for at least a few seconds, he genuinely wanted to kill Marilyn Burns, the actress playing Sally.