Lister is ironing and has put the tomato he was eating to his right on the ironing board. From one shot to the other he suddenly has the tomato in his hand again.
Holly's absence is explained by Lister leaving his bath water running which left Holly out of commission. In White Hole (1991) Holly shuts their self off which powers down the entire ship, yet from here to The Promised Land (2020) Red Dwarf is running fine without Holly.
When the diving bell is being raised from the water tank, its dry.
Rimmer talks about being washed along by millions of gallons of water at "60 knots per hour." Knots are a measure of speed of 1 nautical mile per hour, so he should have said "60 knots."