I'll start:
- Why did the Shambali decide to build their temple with a bottomless pit in the center of it?
- How exactly do sound waves repair damaged machinery and biological injuries?
- Just how many shurikens can Genji hold in his robotic wrist? I know that they probably fold, but even then, there's still only so much space...
- Genji maybe a robot with physically enhanced strength and durability, but that doesn't change the fact that every time he dashes forward, his brain should impact against the back of his skull from the sheer force of the acceleration when he dashes, and then impact forward again when he stops, given that he doesn't decelerate.
- How does Roadhog survive sheer amounts of damage that would otherwise kill any other person not protected by a shield or shrouded in a suit of armor (ie, how does he tank)? I'm pretty sure being a sumo wrestler or having obesity doesn't give bullet proof body armor that allows you to survive showers of 50 caliber bullets from Bastion or double shotgun blasts from Reaper at point blank range.
- What does Torbjorn pour into his gun? Molten slag? Wouldn't carrying all that in his backpack be ludicrously heavy? Also, I seriously doubt that there'd be a way for his little gun to cool the molten hot slag into a solid projectile within the 0.25 seconds the trigger is squeezed.
- The TV tropes page also touched on this: why are the MEKA suits designed so that the operator's arms and the machine's controls hang unprotected outside of the bulletproof glass cockpit? All it takes is for a bullet to hit the operator's exposed arm and the machine won't be piloted optimally, if at all. Damage to control system itself will outright render the suit unusable.