Xbox One turret
From Halopedia, the Halo wiki
The Xbox One turret is an Easter egg in Halo 5: Guardians. It can be seen in any mission or map and only requires a weapon capable of scoping in.
Using a scoped weapon or theater mode free camera, zoom in on the screen in the turret of a Scorpion Tank. The screen will reveal that the computer of the turret of the Scorpion Tank is powered by an Xbox One or is running the Xbox One's operating system. The dashboard on this version of the Xbox One is actually the original Xbox One dashboard that was first launched with the Xbox One. The screen reveals that numerous multimedia apps have been used, such as the Blu-ray disc player. It's also revealed that the last game played was the Halo 5: Guardians Multiplayer Beta.
This is the only turret in the game that has a computerized display that's visible.