Enforced Method Acting: In a good way—Kenneth Branagh and Kevin Kline were actually in the recording booth together (which is rare; actors usually record their lines alone with someone else filling in the other characters) so they could play off each other and banter. It worked beautifully.
What Could Have Been: If this film had made its money back, we could have a whole franchise of them by now. They deliberately sprinkled the film with sequel hooks, and were already in the early stages of plotting out the sequels. One alternative ending to the film actually had them In Medias Res in their next adventure.
It also was going to be revealed at the end that the armadillo was an angel/spirit sent to help Miguel and Tulio. Makes sense when you think about it, considering all the crazy stuff that happens with it around, including pretty much flying through the ball hoop.
The movie itself was originally gonna be a Rated R movie.