Arma 3: Easter Eggs
The "Land_Laptop_02_unfolded_F" Old Laptop has an action to "Get Back to Main Menu" when the mission date is set to 2001-06-22 (Operation Flashpoint release date). Completing the action causes the Old Laptop to display a video showcasing the main menu of Cold War Rearmed. The BIS_fnc_laptopInit function can be used to apply this Easter Egg on other computers.
On December 24th and 25th in system time, some of the trees in Livonia get Christmas ornaments.
Dutch flag and oranges
In one of the IDAP tents that you see at the beginning from the van of Remnants of War, there're a small Dutch flag and a couple of oranges, which is usually you can't see in the gameplay.
This is a reference to the fact that Arma 3 Laws of War (codename orange) is made by the Bohemia Interactive Amsterdam Studio.