Other mistake: A police officer fires two shots, hitting a bank robber in the back. The "bullets" do not make holes in the robber's coat. All they do is create two tiny puffs of dust.
Revealing mistake: A driver pulls out into oncoming traffic and hits another car, It is obvious that when the scene was filmed, the driver stopped just short of the other vehicle. The sound effect of a collision is dubbed in and the front of the two vehicles is never shown.