Continuity mistake: Martin covers the girl with a blanket in the "evening" while the boy is chasing the fireflies. It is never cool enough in GA during the season of fireflies to warrant a blanket. Never. Unless there was some weird and unexplained weather phenomenon. (00:56:00)
Revealing mistake: Near the end of the movie, when Malcolm's partner pulls out his gun and Lester shoots him, the bullet hole in the wall appears before the bullet wound in Paul Giamatti's arm.
Answer: He tried opening the window, but it was stuck. He could also not have gotten through the window without making noise and being discovered. He just wanted to get out of the room without being seen.
raywest ★