8. Joan Of Arc Gives The 15th Century French Army Aerobics - Bill And Ted's Excellent Adventure
This is an interesting case, because unlike a lot of the other entries on this list, it doesn't involve a person going back in time and inventing something. Instead, Bill and Ted bring historical figures with them to the present day and upon being exposed to modern technology, they choose bits of it to take back with them to their own time. Joan of Arc is fascinated by the aerobics class she sees at the San Dimas Mall, which she plans on implementing in the French army upon her return. Could this be a factor in their success against the English while under her leadership? Perhaps. It could also explain why they burned her at the stake, because no one like aerobics. It's also worthy of note that Napoleon takes back a little something of his own. His experience at the water park serves as inspiration for a planned military strike, as he demonstrates at Bill and Ted's presentation. Unfortunately, this strategy was to be used in the French invasion of Russia. You know how one of the most basic rules of war is that you never march on Moscow in winter? Well, it wasn't a rule until Napoleon tried it and was basically laughed out of Russia.