I know it's just a minor thing, but I really liked the effect in the "Pirates of the Caribbean" movie that showed the six pirates swinging in a ball made of bones and climbing their way to the top of the cliff and saving themselves. The Mythbusters tried to recreate the myth that it could be done and messed it up. Big time. In my opinion anyway -- I'm not a scientist.
They used metal to create the ball -- good idea. They had openings at the bottom of the ball large enough for them to crawl through -- bad idea. They used two cables to hold the ball above the ground -- not accurate since in the movie it's supposed to be a single vine. But they did prove that they could climb up the "cliff" by having everyone help climb a cargo net on the side of a building. They really should have replicated the actual conditions. The two safety cables impeded the ability for the momentum to increase.
However, on the same episode, the Build Team made a pulse jet and had an expert come and show them an effective way to build one and how it should run. I wonder how many WWII British survivors watched the episode and had bad memories afterwards? The one their expert built sounded just like a V-1 flying bomb, also known as a "Buzz Bomb" or "Doodlebug" by the British who listened to them as they flew overhead before crashing and exploding. And if you've never heard of the V-1 -- go look it up. They did lots of damage.
Now I'm going to watch the new episode for this week -- any time you make a hot water heater explode on television is awesome.