On the Refectory level, when Gabriel is crawling through the tunnels, you can briefly hear the famous Metal Gear Solid tune. Hideo Kojima, creator of the Metal Gear video game series is one of the producers.
Sir Ian McKellen was the first choice to voice Zobek. But turned it down. McKellan however suggested Sir Patrick Stewart.
The role of Gabriel was originally offered to, Gerard Butler, but he was unavailable.
In an earlier chapter, there is a scroll you can pick up detailing a knights journey into expanding his mind, and with his near omniscient powers, he looked into the universe secrets and discovered "the cake is in fact not a lie!" This is a reference to the game Portal.