One of the houses in the Another Life mission is identified as the Griswald House on the map.
In the NY level, if you start the level dressed as the bunny thief, you have to enter the vault and collect all goldbars for an easter egg to trigger. The previously white mask will turn golden and a pile of wealth will appear with a golden version of the sawed shotgun on top of it.
Sean Bean had a role in the game. He played Mark Faba, aka The Undying, in both a reference to his name, Mark being his middle name and Faba meaning Bean in spanish, and to his career, since almost every single one of his characters dies.
In the elusive target "The Serial Killer", 47 replies to one of The Censor's comments with the line "Maybe I'm not the only one being tested". This is a nod to one of his lines in the prologue/training section in the 2016's Hitman.
In the New York level, there is another easter egg appart from the golden shotgun. If you start as the blue banker, diguise yourself as the job applicant, and successfully complete the job interview, a key will appear in the corner. Head to the deposit area and look for locker 237. This will only happen with the key, if you force the lock nothing will happen. Once you have opened it, a river of blood will "attack" you and a hatchet will be inside. This is a reference to Stanley Kubrick and his 1980 horror classic "The Shinning".