When Bender and Vorobyaninov start working on the propaganda poster, the height of the blank poster (based on the surrounding objects) does not exceed four meters. Later when the finished poster is erected on board of the ship its height is not less that ten meters.
During the boat chase, a white triangle, presumably a sail, is seen as Ostap circles the overturned boat; would not be visible during the true night scene.
On the beach, as chair remains are washed into the sea, a line running to the left bottom of the screen is obvious against white foam.
When Ostap and Ippolit Matveevich are trying to sneak onboard the steamer disguised as loaders, a jet contrail is visible in the upward shot.