David Bateson was originally not intended to return as Agent 47 in Hitman: Absolution, but it was announced in August of 2012 that he would do the voice again. William Mapother was the original voice and motion capture for 47. The motion capture work he had done was still used in the final game.
Kane and Lynch, from the Kane & Lynch game series (another series by IO Interactive) appear in Hitman Absolution. Kane appears in the mission "Welcome to Hope" as the stranger in the bar and Lynch appears in "Birdie's Gift". He can be seen firing a shotgun at the shooting range.
In the mission "One of a Kind", going to the basement of the tailor shows a wall with various newspaper clippings of targets from previous Hitman games.
The role of the head nun, Lasandra Dixon, was cut down somewhat. Vivica A. Fox recorded a scene of the nun praying which was not used in the final game. She would have somehow survived "Attack of the Saints" and ended up in a hospital where 47 would have interrogated her.
Several level concepts were cut from the game, including one involving Sheriff Skurky retreating to a bowling alley, a hot sauce factory (the outfit can still be seen in the level "One of a Kind"), and a grocery store.