Revealing mistake: The money that Micah dumps out of his backpack is very obviously fake. In fact, the $20 bills have Benjamin Franklin's portrait on them.
Revealing mistake: When Mrs. Petrelli is sitting with the dead Peter, just before she lies down on his chest and starts to cry, you can see the "dead" man tilt his head slightly backwards. (00:21:10)
Revealing mistake: Claire Bennett is accidentally tackled when she and Zach are arguing while watching the football game. Apparently, her neck is badly broken in the fall, even twisted a full 180°. However, if you watch closely as she falls, you can see that she is completely fine, stretching out her arms to take the impact before rolling around. She lands on her front, arms stretched out, all in all well prepared for the landing, and rolls around. In the next shot her neck is twisted in a way that simply wouldn't be possible in such a fall. She would have had to have her head stuck under something before rolling over, which she certainly did not. The guy tackling her did not land on top of her either. (00:19:40)
Revealing mistake: When Niki goes to find the 2 million in a case and open it, you can tell that all the money is fake as all the $100 bills have the same numbers. (00:37:37)
Chosen answer: Hiro's powers are still quite unreliable, and a locked closet door isn't a huge obstacle. Since Hiro knows he needs to rescue Ando, it's probably safer to try and bash the door down than risk teleporting to the wrong place or time.