In fact, having any of the great Warner Brothers cartoon characters in this Disney movie made for great cameos since Warner Brothers would put their own movies stars as cartoon cameos in the Looney Tunes and Merrie Melodies shorts. They are a lot more funnier if you know whom is being parodied in some of them.
I saw "Who Framed Roger Rabbit" in the theater when it was first release and people now swear he didn't say it and they may of edited it out of later release and the DVD ....but....
At the end of the scene as Daffy (a black duck) is doing a showboat jam on the piano...Donald grumbles under his breath "G-- D-- N-(word)..."
Yes I know Urban legends contends it didn't happen or you heard wrong... but I remember is very well and remember the others in the theaters look at each other saying "Did Donald just say what I thought he did?"