While underneath the vessel, the submarine Captain orders the vessel to go to 5 meters below surface. This would have caused the submarine to immediately impact the vessel due to her underwater draft(7-10 meters on average).
A modern port fully equipped with a substantial number of Gantry Cranes (used for loading/discharging Container vessels) is shown and referred to as a Naval port of 1968 Russia. There would be no use for them in a Naval port.
The submarine used for filming has been converted to a museum. Stairs inside the submarine used for visitor access are clearly visible. The Soviet "drydock" is also identifiable as the ramp leading up to the side of the ship and not of a style appropriate for a submarine.