More than 8,000 rounds were used for the climactic shoot-out scene.
According to a Warner Brothers executive at the time, when the movie was shown in test screenings and it reached the climax, most of the audience shouted out "Shoot at the bus tires, you idiots!"
The movie's special effects team had a crew of thirty-five people and a budget of $1 million. Special effects expert Chuck Gaspar said, at the time that the movie was made and released, that this movie involved the most challenging special effects tasks he had ever been given up to that time.
The desert hideaway house that got shot up cost $250,000 to construct, and featured 7,000 drilled holes that were used to house explosive squibs which would be set off to simulate gunfire. A team of fifteen men worked eight hour days for a month rigging the dwelling with the squibs for a shoot-out sequence that would result in the demolition and collapses of the building. Special effects coordinator Chuck Gaspar said, "Needless to say, we only had once chance to film the take." And Clint Eastwood said of the sequence that he wanted "not just an ordinary explosion. I wanted the house to collapse to the ground as though it was being eaten away by a gigantic mass of termites."
Fritz Manes: Clint Eastwood's regular producing partner as a helicopter gunman. The appearance was one of seven that Manes has made in Eastwood's movies.