Call of Duty: Modern Warfare contains a Christmas Easter egg (Oxymoron, nest-ce pas?), In which Riley is a guest, also known as the good Call of Duty dog from Call of Duty: Ghosts.
As Multiplayer First spied (which has written a handy guide to finding this information), Easter egg Riley roams the sky at the top of Santa’s sleigh, and Capt. Price sits in the old, funny elf seat.
As a bonus, there is a vague back to the future reference to trigger the whole thing. It’s on the new Winter Docks card (basically, the Docks card has Christmas decorations). Find the clock on the large warehouse outside – it looks like the Hill Valley Courthouse clock from the movie.
When lightning strikes the clock (MP1st tells you how to do it), Riley, the red-nosed Reindog, starts the flyby. Multiplayer First, it is pointed out that the Easter egg can also be triggered in private games, so you can now set it up and see for yourself.
Call of Duty Dog became famous when he appeared in an Ghosts announcement video that showed the infinity ward animators’ meticulous attention to detail. Riley (dog actor’s name: Colin) became a day-zero meme and was most recently seen in the Call of Duty: Modern Warfare campaign on the product packaging for the Actibase console in an open electronics store.