In the level "Blood Brothers" when Yuri has his flashback, the first scene is in Pripyat, Ukraine. This is what the ultranationalists saw on the ground in a Call of Duty Modern Warfare level. The next scene is at the Al- Asad safehouse. Helicopters can be seen coming from the distance. Again, in Modern Warfare, the player is aboard one of these helicopters. And at the scene where Yuri crawls into the terminal in "No Russian" (Modern Warfare 2), he attempts to kill Makarov. If the player goes to the level in Modern Warfare 2 and turns around, Yuri can not be seen struggling to kill Makarov.
William Fitchner plays a Delta operator code named Sandman. In Black Hawk Down, he plays a Delta operator named Sanderson.
The characters Sandman, Frost, Grinch, and Truck are Delta Force operators that fought alongside Captain Price, Soap, Ghost and Roach in Operation: Kingfish in 2013. That is 3 years prior to the time that this game is set.
A promo for the game showed Sam Worthington as one of the lead soldiers. He also starred in Call of Duty: Black Ops and Call of Duty: Black Ops 2
In one of the mission pre load sets with the flash backs in one it shows targets that were taken out and ones that need to. In the ones that have been taken out you can see Kravchenko from Call of Duty Black Ops