I echo the do-not-mix-croc-with-flamigos sentiment, I can NEVER get that to work, the flamingos always just constantly run away and the guests get really upset about it! It's good to know I'm not the only one who has problems with it!
Don't forget your carnivore had male babies and let them grow up in the same exhibit as the dad, or he'll challenge and kill the dad. This happened to me with lions, grizzlies, snow leopards, asiatic black bears...lots of 'em.
Don't put kangaroos in an exhibit with water - they are the WORST at remembering they can't swim!
Don't put rhinos in exhibits with valleys - they like to fall in, get stuck, and get mad!