This page lists all Easter eggs in Hitman: Codename 47.
Terminator's Box of Roses
In the mission Traditions of the Trade, there is a box of roses in the florists shop. It can be obtained by getting Frantz Fuchs' room key, and retrieving the florist's letter from the reception. Delivering the letter to the florist will trick him to giving Agent 47 a box of roses containing a Shotgun. This is a reference to "Terminator 2", where the Terminator retrieves a lever-action shotgun from a box of roses.
In Traditions of the Trade, the peace summit being held is called U.N.F.C.K. FCK is a reference to F.C. Copenhagen or in Danish FC København, the preferred international football team of Io-Interactive.