I know quite a few of the "mistakes," although there aren't many. Here's my favorite from the Haunted Mansion:
"The 'Peppers Ghost' illusion in particular proved very useful for a spooky ballroom scene where a birthday dinner, dancing and a creepy organist can be observed. A rather funny story that comes out of this scene is that when designing the Audio-Animatronics that were shown ballroom dancing, the Imagineers built them as anyone would have, with the men leading the women. However, when they were lit up and mirrored in the glass, it was shown as the opposite, with the women leading the men."
Source:
http://www.weloveorlandofl.com/disn...ook-at-the-history-behind-the-haunted-mansion