Stupidity: Donna runs in to save everyone from the collapsing pylon, dying in the process, despite the fact that Superboy or Raven, both more powerful/resilient, could have stopped it falling without any issues whatsoever. Not even like anyone was distracted - the fight was over, they were all just standing around.
Stupidity: On his own in his helicopter, TC earlier in the episode spots a very hard to catch area of vegetation where supposedly the color of the leaves is different from what's expected. However for the ending, with 4 people in the helicopter, everyone but Magnum misses a giant clearing with a bright red excavator in the open.