The viewer is given the impression that Potemkin gained access to the Black Sea for Russia without firing a shot. In fact, the Russian Empire gained control over the lands which would comprise Novorossiya ("New Russia") by a series of treaties, but only after defeating the Ottoman Empire in a series of conflicts known collectively as the Russo-Turkish Wars (1735-1739; 1768-1774; 1787-1792).
Potemkin introduced Catherine to Mamonov in 1776 after their affair had ended. They did not continue their relationship after she became involved with Mamonov.
Catherine tells Paul "Get a grip!" some 200 years before the phrase entered general use.
As Potemkin boards Catherine's galley for their trip to the Black Sea, he says, "Let's get this show on the road." This was an idiom that didn't exist in their day, but was derived from the practice of taking a Broadway Show on Tour.