6 The Mythbusters once wanted to test the explosive strength of a bomb made out of commonly available materials. They were successful in building a very powerful explosive with easily available material. Considering how effortless it was, they swore to never release the information. 

Once the Mythbusters team decided to test out a very common urban legend that explosives can be created out of widely available materials. Surprisingly, the legend turned out to be true. The team also found out that the materials they used were very easily available. Since such easily obtainable materials can lead to a powerful explosion, the production team decided to not showcase the snippet.

It was wise on their part as it would have been really irresponsible to have taught the people how to make bombs. The team decided to destroy all the footage that they shot and they agreed never to talk about it again. Years later, Adam Savage contacted DARPA, Defense Advanced Research Projects Agency, regarding their discovery. DARPA was requesting information from the public regarding unknown but potential bomb risks. (source)

7 Adam Savage of Mythbusters wanted to test out the myth on pumpkin duck hunting. But the narrative for the particular episode turned out to be so long that he and the team decided to scrap the myth from the episode and never aired it.

In a CNET Magazine interview, Adam Savage revealed that they wanted to test out an urban legend but never got around to do it. He said, “Apparently if you want to hunt ducks, a great method is to float pumpkins in a duck pond so the ducks become acclimatized to pumpkins floating around. Then, you put a pumpkin on your head, presumably with a couple of eyeholes in it, and you swim up to the ducks. They don’t even notice because it’s just another pumpkin.”

Although Adam was very keen to wear a pumpkin and catch a duck, they would not have been able to show the same on television due to the animal rights violation. Plus, it would have been difficult to shoot. So they started putting the difficult parts into narratives. They ended up with so many narratives that it was difficult to accommodate the same into the episode. (1, 2)

8 In the unaired 2010 episode “Testing Grant’s Bones,” Jamie Hyneman announced that they would be performing a series of experiments to find out how strong Grant Imahara’s bones are. The sequence was so cruel that Discovery refused to air the episode.

If aired, this episode might have led to many casualties across the world. The year was 2010 and the episode was to be named “Testing Grant’s Bones.” Jamie Hyneman, one of the co-hosts of the show, announced that they would be testing out how strong are Grant Imahara’s bones. Grant was another co-host in the show.

According to the information available on the Internet, Jamie brought a sledgehammer for the experiment. He then started hitting Grant’s legs repeatedly. It is said that the experiment shattered Grant’s femur and Jamie did not stop even when Grant asked him to. Eventually, he passed out from the pain.

Discovery Channel refused to play this episode on air which was the right decision on their part. Jamie apologized for his actions and claimed that he thought Grant’s bones would have been able to resist the blows. Grant went through an emergency kneecap transplant and had to go through vigorous rounds of physical therapy. He returned to the show six months after the incident. (source)

9 The MythBusters Teeth Challenge was more of an inside joke than a challenge. In the episode, the Mythbusters tried to confirm/bust the myth that Adam had the brownest teeth. This was not aired in the US.

This specific experiment was also known as “Which has the whitest teeth.” This was more an inside joke. Apparently, the team had received numerous emails from viewers across the world complaining about Adam’s brown teeth. So, the team took the myth that “Of all the MythBusters, Adam is the one with the brownest teeth.”

To perform the experiment, Kari had to check the teeth of Jamie, Adam, Tory, and Grant. The first result was that Jamie had the brownest teeth. So, the myth was busted at first. But then Jamie went ahead and got his teeth bleached! So after this, Adam indeed had the brownest teeth. The myth was first busted and then confirmed.

This segment was not aired in the Discovery US version but was aired on the Discovery Europe version. (source)

10 Once the team filled a van with gas containers and rigged them for a slow leak. They were testing the myth that the van would explode after it receives a signal from its keyless remote. The myth was confirmed in the first try and gave the team no chance to expand on the myth’s background or the processes involved.

This segment was called the “Vanishing Van.” The team loaded a van with flammable gas containers. They then created a few leaks in those containers. They wanted to test whether the van would explode in case it was triggered by a signal from a keyless remote.

The experiment turned out to be “too” successful. In the first try, the team was able to shatter the van to bits and pieces. But everything happened so fast that they never got a chance to either record it properly or even provide the explanation behind it. So they decided to not air it instead. (source)