Though Driver doesn't change his clothes during the five-day period in which the film takes place--due to his vengeance being the only thing that matters to him--costume designer Salvador Pérez Jr. actually bought 30 identical sets of clothes for Dwayne Johnson to wear throughout the shoot.
The snub-nose revolver that Driver (Dwayne Johnson) is shooting is a Ruger 2.5" barrel, Super Redhawk in .454 Casull, Cat.# KSRH-2454, Mod.# 5301. Killer (Oliver Jackson-Cohen) uses an H&K P30 with silencer, and a Glock without silencer. Cop (Billy Bob Thornton) uses a Glock.
The Chevelle that Dwayne Johnson drives in the film is a 1971 or 1972 model (as evidenced by the dual taillights), but the front is from the 1970 model (as evidenced by headlights and grille). Also, although the car is badged with the SS (Super Sport) logo, it is in fact a Malibu edition Chevelle as evidenced by the sweep style dash - SS Chevelles have round gauges.