There are many references to other Bethesda games in The Old Blood. There's a Quake bazooka on the car key at the start of the game, there's the iconic horned helmet from Skyrim which can be used for armor, and there's a Nuka Cola label on a vending machine from the Fallout franchise.
In one of the rooms in Castle Wolfenstein, you'll see a stuffed toy of a Cacodemon from Doom (2016).
Only released on the PlayStation 4, Xbox One, and PC, unlike Wolfenstein: The New Order which was released on those platforms and the PlayStation 3 and Xbox 360.