As Stan and Ollie enter the yacht's galley for the first time, Stan all of a sudden has lost a lot of weight (and no wonder. The two scenes were filmed months apart between Stan's illness and hospitalization, where he host around 50 pounds).
The goof item below may give away important plot points.
Stan and Ollie have been assured that the island they have inherited is absolutely tax-free. Yet, when they finally arrive at the end of the picture, the island is seized by the government for non-payment of inheritance taxes.