After Dr Burke is first seen in the Breeches Bouy, with ropes extending out of shot towards the Russian ship, the view changes to the Russian ship approaching, and there are no ropes between the vessels.
When Captain Spratt is knocked backwards into the swimming pool, it is clearly a stunt double. The stunt-person has far too much hair and is obviously slimmer than actor Robert Morley.
Leslie Phillips wears Simon Dee's clothes when he puts his in the wash. They fit perfectly but when they stand together Simon Dee is 5 to 6 inches taller that Leslie Phillips.