From Wikipedia:

"The finished film contains footage of a real helicopter crash. In a scene showing law enforcement officers firing their weapons to ward off tomatoes in a field, a $60,000 Hiller Aircraft UH-12E that had been rented for the production was supposed to have landed in the tomato patch behind the officers, but during the landing, its tail rotor struck the ground, causing the craft to spin out of control near the ground, roll over, and burst into flames. The helicopter pilot escaped without serious injury.[2] The crash was accidentally caught on film and was later worked into the film."