From Halopedia, the Halo wiki
Halo Kart is an Easter egg found on the Halo 5: Guardians campaign level Evacuation. It can only be found on 4-player cooperative play. When the Easter egg is activated, all four players in the session would be teleported to another location with four Mongooses and a countdown timer to start the race.
On April 4, 2021 Patrick Wren, a designer for 343 Industries, responded to a tweet on Twitter that asked developers what were the best Easter eggs they hid in a game. Wren stated that there is a Halo Kart Easter egg on the mission Evacuation in Halo 5: Guardians only accessible while in 4 player co-op mode and that the winner of the race gets a heavy weapon. The next day, on April 5, Wren tweeted a hint in a form of a riddle, "Four Spartans begin at the station, To seek Evacuation sensation, To race out of the gate, Simply stand there and wait, A duration of his designation." Wren makes a reference to John-117 by saying designation, as the designation most commonly known is 117 which is the number of seconds needed to wait at the gate and activate the Easter egg.
To perform the Easter egg, it has to be done during the first two minutes once the players start the level. When the players gain control of their characters, to the right, there is a door where the players will have to wait idly for 117 seconds. Once the Easter egg is successfully triggered, all enemies on the level during the evacuation section of the level will despawn. When completing the Easter egg, the player who arrives at the final destination first is granted a random power weapon to use during the remaining parts of the level.
- Twitter, Patrick Wren (@Witdarkstar): "There is a Halo Kart racing for four player coop with mongeese in my mission Evacuation. Winner gets heavy weapons at the end of the race."