What If... The Watcher Broke His Oath? - S1-E9
Stupidity: Ultron says he can destroy galaxies with a thought. So regardless of Dr. Strange's protection spells, he could destroy the planet they're all standing on, or evaporate the atmosphere, leaving them all suffocating in space, and just step away from the fight entirely while they die.
What If... Ultron Won? - S1-E8
Stupidity: For some reason, Ultron's Mind Stone is a death ray thousand times more powerful than anything ever seen; not only it one-shots Thanos wearing all the other stones, but effortlessly dissolves the star-forged Gauntlet that is meant to withstand the power of all gems combined.
What If... The Watcher Broke His Oath? - S1-E9
Stupidity: Infinity Stones are so particular to each universe that a gem-destroying tool coming from another universe can't do anything to them, but on the other hand Ultron has no problem using them in any other universe, including where The Watcher is hidden, which should be extraneous to space and time much like the TVA (where the stones are worthless paper weights).