"Brancoleone alle crociate" looks a lot like the blueprint to "Monty Python and the Holy Grail" (complete with animated bits), but unfortunately it's nowhere near as funny. The actors most definitely aren't the problem, because they're great and really seem to have fun with this project. The director does a pretty good job as well, the movie bathes in a very outrageous atmosphere that's really fitting for the source material. No, to me it's purely a script thing. The jokes are mostly just flat and predictable, it's absurd comedy by writers who haven't really gotten the gist of it yet. Take the running gag with the king who rhymes every sentence for example, you know there are some good scenes in there but they can't fish them out. Inevitably some stuff does work (the guy using another guy as his horse is a nice touch), but the laughs are few and far apart. However, the movie is still enjoyable for some reason, mainly because I'm a sucker for this kind of pseudo-historical comedy. Not the greatest in its genre, but it's watchable.
One last thing: given that I don't understand Italian, I saw this movie subtitled in French. The jokes may well be hilarious in their original language, who knows.