Sword-wielding Elites are apparently programmed to berserker rush any player they see, regardless if the player is driving a forklift, which has just enough acceleration to kill them.
Some of the easter eggs are absolutely hilarious. For example, finding a dance club of Grunts dancing to music with a Brute as a DJ.
If you do the Covenant disco Easter Egg, they'll ignore you til you either kill one of the Grunts or Brutes, or destroy the generator. When you do, the record will scratch and the music will stop as if to say, "HUH?!" Everything will be still for a moment before all heck breaks loose.
Occasionally, invoking friendly fire will cause a partner to threaten to teabag you.
Turn on the subtitles for cutscenes, then watch the cutscene that plays before the mission Tip of the Spear, with all the vehicles flying or driving in to battle. Jun's ordinary line, "Discharge link is loud and clear!", becomes subtitled as "Time to bake that cake we made last night!"
One of Jun's Firefight lines when he gets the rocket launcher: "Pardon me while I whip this out!"