On the campaign level "Throttle", it's possible to find an RPG Launcher by climbing to the top of a column and onto a glitched part of a building. The building can be located behind one of the turrets that the player needs to destroy. The RPG appears to be a leftover asset from previous Call of Duty titles, and was likely left by a developer by accident.
On the mission Throttle, there is a difficult to access test weapon called WEAPON_RPG. It is an old RPG-7 and appears to not have been intended to show up on the map as it does very little damage and does not possess firing noises.
Though the game was never released for Wii U, the system's logo can be found bunched with the rest of the system logos in the files for the game's official website. This hints that Sledgehammer Games, the subsidiary of ##Activision## that developed the game, originally planned to bring the game to Wii U.