Stupidity: After the power cuts out, Thawne realises an obvious hiding spot and races to the secret room. He sees it's empty and just...stops looking? We literally just saw The Flash take a fraction of a second to scout out an entire enemy base we're told was 22km away! While he's dawdling in the secret room, Iris and Felicity get to Kara, knock out the guards, and get her down the corridor to the lift. He could have checked the entirety of Star Labs 10 times over in that time.
Stupidity: The team knows that Eva can snatch people through any reflective surface, and make a great show of killing the lights to prevent reflections...which are then replaced by emergency lighting, rendering the whole process pointless. They also drop shutters over the outside of the windows, leaving the reflective windows themselves unprotected inside the lab! And Barry promptly stares pensively into one at close range...and is of course snatched by Eva.