The anaesthetic weapon, which can be used to non-lethally incapacitate enemies, originally had a different appearance. It was originally depicted as a jar with a rag, and Agent 47 would have presumably used the chemical-soaked rag to knock out enemies. It was replaced with a hypodermic needle in the final game.
During the mission '"Invitation to a Party", the newspaper located in the offices says "FCK Danish Champions 2001". This is a reference to the Danish Copenhagen soccer team FC KÃ¸behavn, who won the Danish soccer tournament in 2001. The smaller headline reads "FC KÃ¸benhavn beats Bundby". Bundby is actually a town called BrÃ¸ndby, the wrong name is simply a joke from the developers. "Bundby" translates to "Bottom City" while "BrÃ¸ndby" means "Well City".