During the Sword fight scene, 47 pulls a katana out of a dead agent's hand, in order to use it. It is covered and dripping with blood. However when he comes to use it a few seconds later, it is clean as can be.
When 47 crashes through the hotel window and the kids turn around, you can see that they're playing a videogame. The game is "Hitman: Blood Money", the first mission to be exact.