In previous games, Covenant troops could be understood. In this game, they cannot.
Objects such as empty cartridges do not behave properly in micro-gravity.
In the Spartan Ops campaign, upon closing the last door to the engine room, Covenant forces appear in the room even though there is no other way in.
The shields that the Player is tasked with taking out do not inhibit the progress of the Mammoth at all, with the Mammoth even making it around the area before the Player gets there.
A target the size of the turrets should not need a target designator to target.
In the Spartan Ops campaign, the visors of the Players' character models do not match the first-person view.
If the Player manages to press against a Covenant drop pod, he can partially clip through it.
After the Players kill multiple enemies, the rest of the enemies get target markers painted on them. It makes more sense for them to be painted immediately instead of waiting for some to be killed.
In the Spartan Ops campaign, a barrier can be bypassed by overloading its fusion coils through a panel. It should have safeguards to prevent this.
When evacuating the Forward Unto Dawn, the Master Chief asks where the escape pods are, despite passing through the area minutes before.