When Mrs Silver and Mr. Pringle come to his flat for a meal he doesn't have three wine glasses but in a later fleeting 2 or 3 second shot there are three wine glasses on the meal table.
Mr. Hoppy first purchases 16 tortoises in order to begin "growing" Mrs. Silver's pet. At 27:30 minutes, 16 specimens are seen swimming in an aquarium. Tortoises are land animals and do not ordinarily swim in water. Those must be aquatic turtles instead.
At the end of the film Mrs Silver and Mr Hoppy are dancing together. Mr Hoppy moves Mrs Silvers hand to his mouth for a kiss. He is actually kissing the back of his own hand.
Mr Pringle twice says that the moment of his birth came about as a result of his father driving too quickly over a speed bump. This would make Pringle, at the time of the film's release (2015) no older than 32 years of age as speed bumps weren't introduced in the UK until 1987. Pringle, appears to be of a similar age to Mrs Silver, played by Judith Dench, and Mr Hoppy, played by Dustin Hoffman, who were born in 1934 and 1937 respectively.