Why It Was Hell: For starters, Universal hadn't agreed upon a budget for the movie until it had already been shooting for a month, and when the studio finally came up with their number ($17.5 million), director John Landis had already burned through a large portion of it, causing the budget to ultimately balloon to $30 million. Most of the production's mayhem, however, can be attributed to the hard-partying John Belushi, whose drug use caused him to frequently arrive late to set, to the extent that a frustrated Landis ended up flushing his cocaine stash and punching him when he became aggressive. Cocaine was even in the movie's budget for night-time shoots, leading to one infamous incident in which Belushi stumbled into a nearby resident's house and stole food from their fridge. Ironically, drugs were needed to complete the shoot, as after Belushi injured his knee while skateboarding, he had to be given a strong does of anesthetics to film the final scene. Was It Worth It?: Despite enormous concerns over the film's budget and ability to connect with audiences, it opened to strong reviews and ultimately became a classic in its own right, grossing close to 4x its eventual price tag. A belated 1998 sequel, however (made without John Belushi, who died of a drug overdose a few years after the original's release), was a critical and commercial dud. Which out of control movie set did you find the most terrifying? Got any other cool on-set stories? Shout them out in the comments!