Other mistake: The calendar on the wall in Porky's kitchen shows April as having 31 days instead of 30.
Daffy Duck Hunt (1949)
1 other mistake - chronological order
Continuity mistake: When Porky realises that they are celebrating Christmas in April instead of December, the numbers on the month of April on the calendar change position between shots.
Daffy Duck: Why the copious flow of lachrymal fluid, my garrulous canine?