The Rise of Catherine the GreatGoofs

When the Grand Duke Peter is talking with the guard at the bottom of the stairs about Ivan Ivanovich, the guard's crossed belts on his chest are repositioned when the scene cuts to a close up of the guard.

When Peter marries Catherine in a Russian Orthodox service, they respond to the the lines "Do you take this man/woman to be your lawful wedded husband/wife... until death do you part?" These lines are not part of a traditional Orthodox service. The bride and groom usually do not say anything during the service.