As Thunderbolt and Lightfoot are being chased by Red and Eddie, Lightfoot careens the stolen Buick Riviera off the highway and down a steep embankment. Clint Eastwood's character (Thunderbolt, in the passenger seat) has obviously been replaced with a dummy. In addition, in some of the shots you can clearly see a large camera assembly, mounted behind the back seating area of the Riviera.
Red and Eddie's revolvers have "silencers". Revolvers cannot be silenced at the muzzle, because most of the noise of the shot occurs and escapes at the rear of the gun at the cartridge cylinder, which has open spaces at the front and rear to facilitate its movement in the frame as the gun is cocked and fired.
When Red and Lightfoot are opening the wooden crates with crowbars, the lid on Red's crate opens completely with one pry and the Lightfoot even lifts the top on his crate up before he uses the crowbar.