When Claire gets home, her hair has been washed and styled, even though her feet are still muddy from the night in the river, so she hasn't had a chance to clean up.
When Mohinder and Peter are talking on the train, Peter's wristwatch moves forward 8 minutes between two shots that only last a couple of seconds
On the back of the book from "Chandra Suresh" the picture is changed. In episode 3 you can see his bald head. But in episode 4, in the "review" of episode 3, he has a 'tulband' on his head.
After Nathan Petrelli has been thrown back into a chair by Jessica Sanders, his left hand alternates between resting against his chin and resting on the chair's arm between shots.
When Niki and Nathan are in his hotel room, they are commenting on how high up they are. Yet when Niki is at the elevator, the arrows clearly only point upward, and there is only one button (an up button?) Why would she need to go up if she were on a high floor already? The elevator should be either two way, or simply downward.
In the scene where Claire is driving the quarterbacks car she is shown driving a manual transmission while the audio is of an automatic transmission.