Best history movie mistakes of 1988
Continuity mistake: The actress loads her 35mm Praktica camera with Kodak film. That's not really strange, but the film is situated in 1968 around the invasion of the Russians in Prague. The film cassette is clearly visible as having DX coding on one side for setting the film speed automatically. This feature had yet to be invented in 1968, because it was released in the early 80's.
Deliberate mistake: As the Soviet tank starts rolling, the tank commander obviously uses a hidden step to mount the tank. Soviet T-55/T-62 type tanks did not have steps for mounting by the wheels and axles; to mount a rolling tank using the moving wheels or spinning axles would result in the mounter being immediately crushed and killed.
Factual error: At the beginning of the film, in the shots of the players in action being voiced over by Comiskey, Cicotte is marking the ball with his fingernail. You can see the modern logo of the sporting goods company "Rawlings" on the ball. It can be seen even more later in the film when Comiskey's assistant is turning a team-autographed ball over in his hands. Rawlings did not start making official major league baseballs until 1976, and even if they had made them in 1919, they very likely did not have the exact same logo.