Instant Replay

I was not watching the "Perfect Game" last night by Armando Galarraga, because I was too busy watching the Flyers' 4-3 overtime win over the Blackhawks. What I am struck by is the discrepancy in instant replay rules between hockey and baseball. Baseball supposedly cannot have instant replay because it will break up the flow of the game. However, hockey which has a lot more natural flow to the game has instant replay. In last night's game there were two key calls that went to instant replay, one giving the Flyers a goal and one not giving them a goal in overtime. The first one went to replay after the game continued for a minute and a half. If hockey can have instant replay despite problems with the flow of the game, then I cannot see how baseball cannot. Admittedly hockey needs instant replay more in that both of the calls would have been impossible to necessarily get right without replay, whereas the ump in the baseball game should have gotten the play at first base right anyway.

P.S. After writing this but before posting, I found another argument along the same lines.