Fireball stungun: This turned out about as I expected. It seemed pretty plausible when it was done on
CSI. The one thing that seemed odd to me was Adam being surprised that the police-issue pepper spray didn't work, because a key component of the CSI episode was that it wasn't police-issue spray, and the CSI team specifically determined that police-issue spray wouldn't combust. But that proved a minor issue, since the Mythbusters did get around to testing a variety of different sprays.
And the end result seemed pretty straightforward. High-voltage ignition source, flammable liquid, flammable fabric, oxygen atmosphere being a given -- it would've been surprising if it didn't combust.
In fact, it makes me wonder if it's a good idea to design tasers in such a way that they have sparks generated. What if the suspect has spilled alcohol or turpentine or something on his clothes?
Adam making his own shirt was an interesting touch. You never know what skills these guys will pull out of their hats next.
The "Jamie's-eye view from inside the hazmat suit" shot was a cute touch.
In the gratuitous last bit with the flamethrower, that was an odd human analogue they used -- basically a skeleton made of rebar. I wonder what that was originally. Something for a commercial? An art project? (Adam's line about Grant having a whole staff of such robotic servants at his castle was kind of creepy. I mean, that would make one scary-looking robot army.)
After seeing a CSI clip in
Mythbusters, I've realized something: Nick Stokes reminds me a bit of Tory Belleci.
Fireworks launch: The myth was so vaguely defined that it would've been pretty much impossible to give it more than a Plausible. But the vagueness gave them a lot of room to play around. The different designs they came up with were interesting. I think the problem with Grant's chevron-shaped design was that too much of the thrust was wasted perpendicular to the vector of motion. I understand the principle of using that to stabilize it, but there just wasn't enough forward thrust left over. As for Tory's, the X-Wing/
Babylon 5-Starfury approach looked awesome, but I don't think the struts were strong enough structurally, so the whole thing just broke apart. I loved it, though, that the rocket itself went nowhere but the pilot was flung a considerable distance. That's something Chuck Jones never thought of subjecting the Coyote to.

(And did anyone else notice that Tory's Mini-Buster had its face drawn to look kinda like Munch's
The Scream?)
Kari's design was intriguing and counterintuitive. I'm not sure all that downward thrust against the neck and shoulders would be particularly safe, though. And it's ironic that the prediction Grant made about the small-scale design -- that it would be too back-heavy and just go into a spin -- didn't come true for the small-scale but did for the full-scale.
I think their rationale for calling it Busted was reasonable. True, if they'd tweaked the design still further, fixed the problem of the feet lifting up, they might've been able to get a fairly long flight. But as they said, they had a lot more resources, time, and expertise to apply than the mythical German
Raketenmann, and even so they weren't quite able to make it work. So some guy acting on a whim and trying to pull this off would probably have sent himself only to the hospital or the morgue.