The short's plot makes perfect sense when you realize the song Steamboat Willie is named after, "Steamboat Bill," (Which is the song Mickey is whistling, and is the credit song for this video) is about a captain accidentally blowing his steamboat up while trying to beat a record.
The Cabin Boy and the Chambermaid's bodies were never found. They may well have escaped and are (or at least were, given the film's timeframe) still alive and at large.
