But during a commercial break they have a paid-for-by-the-Army mini-myth which was something like "if you had N Lego bricks you could build a tower reaching all the way to the moon!"
No, you couldn't. This is Mythbusters, dammit, where such sloppy linear approximations shouldn't be tolerated. Even ignoring shear issues, the sheer weight of the tower would crush the bottom blocks.
Or, if they've tried it out, when can I buy a ticket on the Mythbusters/Lego Space Elevator?