Around halfway through the movie, Calvin Fuller (Thomas Ian Nicholas) is in King Arthur's castle and says he wants to cook something more tasteful. So he goes for a couple of cheeseburgers. He takes a tomato from the bowl on the table, slices it and puts it in the buns along with cheese, lettuce and meat. Yeah, it tastes good, but... oops, King Arthur lived (if he ever did) in the 6th century and tomatoes were brought in Europe from America in 15th-16th century. Pretty big mistake, isn't it?