Despite the movie taking place in the mid-to-late 1960s, a clearly very modern train from at least the late '70s can be seen moving past Selma's house early in the film.
When Bill's police-issue pistol is first seen, it is a revolver (likely a .38 snub). However, when later in the film it is a semi-automatic M1911, which is not a revolver. While both types of weapons were used by the police of the time, Bill is only mentioned to have one pistol, his standard-issue one from the police force, and is never mentioned to have two handguns.
In the final scene, Selma's hair falls in front of her face when the hood is taken off. In the next shot, it's been brushed back, which she couldn't have done because her hands were tied.
When Bill tells Selma he has no money, Selma's hair repeatedly switches from being over her ears to being tucked behind them.
Selma's son's surname should be Jezek, not Jezková.
When Selma knocks on the door and her foreman answers, it opens from the wrong direction, and they are clearly not in the same factory building.
When Kathy shows up to help Selma on the night shift, her mouth is clearly not saying the words that are heard.
Although Selma is from Czechoslovakia, her accent is neither Czech nor Slovak.
Selma nicknames Kathy with the wrong pronunciation - Kvalda, instead of Tsvalda. If Selma was of Czech origin, she wouldn't make such a mistake.
The name Oldrich Novy is said with a wrong pronunciation by the Czech characters, because Czech digraph 'ch' isn't used in English.