Continuity mistake: When Hiro gives Charlie the Japanese phrase book, Charlie flips the book over to look at the back cover, then flips it frontwards again. In the next shot, she's instantly looking at the back cover again. (00:16:20)
Continuity mistake: When Charlie invites Hiro over to help celebrate her birthday, the invite is almost immediately after she says "hold that thought" and walks away from his booth. But in that scene in the previous episode, Charlie was already across the room with the other townspeople when she signaled Hiro to come over.
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.