Director Sam Peckinpah allowed actor and long-time associate James Coburn to work on the movie as a second-unit director to get his DGA card, and rumour has it that Coburn actually directed some scenes when Peckinpah was "unwell."
The Mack truck in the shootout scene on the Bridge was actually damaged so badly that it broke down just moments before filming the scene and had to be pushed across the bridge by a bulldozer to complete the scene.
Sam Peckinpah's original cut was around three and a half hours long. Since he wasn't involved in post production, movie was edited by studio staff and editor Garth Craven down to 1 hour and 50 minutes long running time.
The song "Old home filler-up and keep on a truckin cafe" had been written in 1974 by Bill Fries (aka CW McCall) for a series of bread commercials in Nebraska , and the success of the song and commercials inspired Fries to write more trucking type songs, including Convoy , resulting in increased interest with CB radios and trucker lingo. By the time the movie went into production in 1977, the trend had already faded, but that didn't stop it from being a box office hit.
Although the movie was inspired by the 1976 song of the same title, the song really didn't have much of a plot. So after the screenplay was written, Bill Fries (aka CW McCall) recorded a new version of the song, with lyrics that incorporated the characters and events of the film. This is the version that is played during the final credits.
Filming finally wrapped in early September 1977, two months behind schedule and $3,000,000 over-budget. A month later, however, Sam Peckinpah was assigned to re-shoot several scenes, which he did without incident. After several months of editing, Peckinpah delivered a rough cut without bothering to include the final half-hour of the movie. EMI finally lost patience with Peckinpah and took over editing; yet again, Peckinpah was barred from finishing his own movie.
On the day the climactic funeral scene was set to film, with the cast, crew and 3,000 extras assembled, Sam Peckinpah locked himself in his trailer for twelve hours, refusing to communicate with anyone. He also fired several crew members and assistants as filming dragged on. With their director incapacitated, James Coburn and the other assistant directors essentially finished directing Convoy themselves.
Sam Peckinpah was taking heavy amounts of cocaine, Quaaludes and vitamin shots that left him both irritable and irrational. At one point, Peckinpah called his nephew David from the set, ranting that Steve McQueen and the Executive Car Leasing Company were conspiring to kill him.
Bill Norton's original script was a lighthearted action comedy similar to Smokey and the Bandit (1977). He pitched the script to EMI, who offered the script to Sam Peckinpah, then finishing post-production on Cross of Iron (1977). Though dubious about the project's potential, Peckinpah agreed on condition that he had complete control over the film. The studio agreed, and trouble promptly began. Peckinpah immediately started rewriting Norton's script, envisioning it as a modern-day Western with truckers fighting against crooked lawmen and unfair interstate regulations, while also adding heavy-handed political satire.
The famous scene where the tanker truck goes off a bridge and explodes was filmed in Needles, California, on a one-way bridge over the Colorado River between Arizona and Needles. The Needles City Fire Department provided fire protection during this scene. The bridge was soon thereafter removed as a new span connected the two sides of the river.
The "tank" used at the end of the movie is actually an M42 40mm Self-Propelled Anti-Aircraft Gun called a "Duster". It was used in the Korean War for anti-aircraft and in the Vietnam War for truck convoy protection duty.
The overturning of Widow Woman's truck wasn't supposed to happen and was subsequently written into the script after it occurred. Moreover, stuntman Bob Herron was originally supposed to crash into the barn and land in said barn after Sheriff Lyle Wallace's car goes through the billboard.