Revealing mistake: When the businessman rushes back into his bed after closing the window that Daffy opened, he is wearing his normal trousers.
A Pest in the House (1947)
1 revealing mistake - chronological order
Other mistake: When Daffy is helping the guest to his room, he looks at his keys as to which one would open it. When he finds the right key, he somehow manages to open the door without unlocking it.