Continuity mistake: When Don is caught by the cop while splashing around in the puddle during "Singin' in the Rain", Don's left hand jumps from his umbrella handle to down at his side between shots.
Other mistake: When Sylvester is looking in the mirror whilst trying on hats, one of the hats has a price tag on it which reads $105.95. However, you can see the price numbering is the right way round - it should be back to front.