Due to the marketing, most people just expected a nice tribute completely done in the style of the classic Mickey shorts... then the Fourth Wall came crashing down.
There is no recording of Walt Disney ever saying the word "red" in Mickey's voice, but by this point the production team was dead-set on only using Disney recordings, so they spent two weeks compositing the word together from old audio of the sounds "r", "eh", and "d" taken from three different words.
The absolutely seamless blending of traditional and CG animation - the latter stylized to resemble rubberhose animation no less! Visual Effects of Awesome indeed.
