A couple of glitches I encountered.
In the 1st mission, when running away from the Banished at the end, I was trying to ram grunts, and somehow my warthog jumped off the cliff and landed on the extraction pad. Thus I ended up on the other side of the light bridge, but the mission would not end because I never activated the light bridge (personally I think I should be given a bonus medal for getting all 3 Spartans to the extraction point, lol). Probably a freak occurrence, but I think some sort of explosion propelled the warthog off the path.
In the mission Under the Dark, in the second part where you need to put 3 Kodiaks at the marked location, I accidently put 1 Spartan in one of them earlier in the mission, and when it came time to place the last Kodiak in the correct spot, when the game took over the movement and turned the Kodiak Orange, it refused to move to the last spot. I suspect that it did not like Spartan 130 being in the Kodiak. Thus, I had to play the entire mission over from the very beginning.
I wish there were checkpoints on some of the missions, as playing the entire mission because of a glitch at the end of the mission is annoying.