I've noticed on Heroes that when they start off from a scene they showed on the previous episode that the scene is slightly different, like it's another shooting of the same scene, or maybe just a different cut.
For example, towards the end of season 1 episode 4, when Hiro appears to Peter on the train, Peter says: "How's this happening?" and Hiro responds with: "Sorry if I scared you; you look different without the scar", but when the same scene is shown at beginning of the next episode (season 1 episode 5), Peter says: "What?! Are you doing this?" and Hiro just responds with: "You look different without the scar". Why is that?