This was one of my overall favorite episodes, probably because I'm a big proponent of the space program, and have always found moon landing conspiracy theorists incredibly annoying. Each of the most popular arguments for the falsification of the lunar landing is satisfyingly debunked (footprints can conceivably be made in moon dust, that wasn't wind making the flag move, etc). But MythBusters effectively closed the case when they showed the reflectors. See, anyone with a powerful enough telescope and the right coordinates can see the reflectors left on the lunar surface by the astronauts. And that's rather difficult to explain away, I'd say.
4) The Coffin Punch from Kill Bill
So, you've been buried alive and left to rot like the Bride. Can your awesome kung fu skills allow you to punch your way through the wood of the casket lid? (You do have awesome kung fu skills, right? 'Cause that's kinda important.) And even if you can accomplish this, could you then dig your way out of the tons of earth that will start rushing in immediately before you're crushed and asphyxiated? MythBusters' short answer: No to the first part... and no again to the second, even assuming the first was possible. The crew tried with only a fraction of the actual amount of dirt a real prospective grave-escaper would be dealing with, and there's just no way to get out of the casket and work your way to the surface before the dirt incapacitates you. It's too fast and too heavy. Bummer.
3) The Ninja Arrow Catch
Ninjas hold a place of honor in the halls of nerd badassery, and MythBusters devoted not one, but two episodes to their mythical prowess. This was another disputed and revisited myth, appearing in both ninja-themed specials. Originally, Adam and Jamie declared this myth busted when their arrow-catching robot could not achieve this feat, but the fans insisted they try again with a real ninja before closing the case. So they found one!
Granted, their ninja had them firing arrows on his own terms: He decided how far away Jamie would stand, and would only let him draw back three-quarters of the way on his bow. But he did catch an arrow in mid-flight! Okay, not exactly consistently, but he proved it's possible, and forced the MythBusters to revise their conclusion from "Busted" to "Plausible." Furthermore, he demonstrated that ninjas don't really need to catch arrows, because deflecting it and then dispatching the archer before he could get off another shot is much more practical, and well within a ninja's capabilities.
2) The Motorcycle Flip from Indiana Jones and the Last Crusade
This actually isn't the first Indiana Jones-based myth featured on the show; Adam is an Indy fanatic (viewers are familiar with his regular donning of the trademark leather jacket and fedora), and previously the crew had covered two myths from Temple of Doom ("Falling Through Awnings", and "Life Raft Parachute"). This stunt from Last Crusade was the most surprising, though, because it seems so reasonable: Flagpole is stuck in motorcycle spokes, motorcycle goes ass over teakettle. When you abruptly stop something like a motorcycle engine, all that kinetic energy has to go somewhere, right? Wrong. Turns out it's practically impossible to get a pole between a running motorcycle's spokes -- they had to use special wheels simply to test the effect of this act -- and even if you get one jammed in there, all it'll do is stop the bike dead. Still, here's hoping the guys get around to testing the nuked refrigerator from Crystal Skull.
1) The Gorn Cannon from Star Trek
Quick run-down of the classic Star Trek episode "Arena" for those who may not have seen it: Kirk and the captain of a Gorn vessel are transported to an uninhabited planet by some of the Trek universe's ubiquitous godlike aliens. There's nothing on the planet but various mineral deposits, which the beings claim will serve as weapons if the captains can figure out how to use them. Kirk figures out how to make gunpowder, builds a bamboo cannon, and uses it to blow thr hell out of the Gorn by firing diamonds at him.
Alas, Kirk's legendary Gorn Cannon got itself busted. Seems that while Kirk got the gunpowder recipe right, as in all cooking it's not enough to know what the ingredients are, you have to know how much to use. If you don't know the precise quantities of each mineral to add to make gunpowder, you won't get squat. Of course, this is a moot point, because even with professional grade gunpowder, a length of bamboo like the one from the show would make a pretty piss poor cannon -- even if you could get it to fire, it'd be all but unaimable. Sad, really.