James C. Burns and Sam Worthington did not return to reprise the characters Frank Woods and Alex Mason, respectively. When asked why he didn't return, Burns said that Activision never asked him. As for Worthington, it was simply because he was busy with Avatar: Way of the Water (2022).
The Campaign is set between Call of duty Black Ops and Call of Duty Black Ops 2
The Vietnam war started in 1964 and lasted 11 years until 1975. The trailer begins in 1968, most likely the Tet Offensive where the Vietnamese struck hard across the entire republic for the first time, showing the Americans that this war was a long way from over. The North Vietnamese Conventionally trained army. Along with unconventional Vietcong(NLF) guerrillas could unite and co-ordinate a strategic attack against targets all over the country at once. This was a game changer. All Of which was covertly supported by assistance from USSR Spetznatz Special Forces and KGB intelligence as a proxy war against American foreign policy.
A cutscene within the game shows F/A-18 Hornet aircraft taking off from an aircraft carrier. This part of the game is set in 1981. While the aircraft's first flight was in 1978, the F/A-18 did not enter service until 1983 with the United States Marine Corps, followed by its induction into service with the United States Navy in 1984.