Other mistake: This is a UK/US vocal talent variation. In the UK version the voice of the Ugly Stepsister is that of UK TV/Radio Presenter Jonathan Ross yet the vocal talents are credited as CNN talk show host Larry King. Also, the voice of the Red Carpet Reporter is none other than UK Pop Idol Extra presenter Kate Thornton, yet again, the voice is credited as Hollywood reporter Joan Rivers, whom the physical appearance of the character is based on. (00:28:20 - 01:03:50)
Other mistake: In the scene where Shrek wakes up to find himself human in the barn, Puss is holding the potion bottle, reading its disclaimer. What is wrong, is the shadows on the floor (casting behind him) don't match the shadows on his body (casting to the right side). (00:51:50)
Other mistake: When the royal messenger informs Shrek and Fiona about the royal ball the scroll he is reading from is not open enough for him to be able to say what is written.
Answer: The gag is that the wolf has developed a peculiar sexual fetish: he wears women's clothing for fun and is attracted to pigs. The magazine was changed for the trailer to be less suggestive (and thus to make the trailer G-rated).