* FanNickname: Rtas 'Vadum (the Elite counterpart to Lord Hood) is also known by fans as "Half-Jaw," because, well, [[ExactlyWhatItSaysOnTheTin you know]]... Later, the novella ''Literature/HaloShadowOfIntent'' (written by one of {{Creator/Bungie}}-era ''Halo''[='s=] main story guys) [[AscendedFanon established "Half-Jaw" as an official in-universe nickname]].
* TheOtherDarrin: Miranda Keyes had her voice actress changed from Creator/JulieBenz to Justis Bolding.
* WhatCouldHaveBeen:
** The level "Cortana" went through several iterations. In one version, Cortana would pilot a damaged Scarab to battle the Gravemind while the Chief would fight off Flood boarders. In another, the Chief would pass through the Mausoleum of the Arbiter and fight a ton of infected Arbiters.
** ''Halo 2'' was originally to have ended where ''Halo 3''[='s=] first half left off (the portal to the Ark was the Ark itself), making much of the latter's campaign filler and resulting in a relatively story-cramped installment.