* AuthorsSavingThrow: The developers explained that the reason why Crimson Heads were not included in ''[[VideoGame/ResidentEvil0 0]]'' (after being retroactively introduced in the ''[[VideoGame/ResidentEvil REmake]]'') is because Rebecca Chambers and Billy Coen don't spent much around the same place as Alpha Team in ''[=REmake=]''.
* DemonicSpiders:
** The leech zombies, without a shadow of a doubt. Tough as nails with an insanely long reach, they cause considerable damage when they hit, and when they die, they ''explode'' for even more damage. Luckily, [[KillItWithFire fire kills them]] fairly quickly, mitigating the annoyance a bit.
** Eliminators are small, soak up more damage than they have a right to, attack in packs, and like dodging bullets.
* EnsembleDarkHorse: Billy. So much to the point fans desperately want Creator/{{Capcom}} [[spoiler: to reveal his fate.]]
** Despite the fact she's the focal character of the game, Rebecca is herself one as far as the series itself is concerned. Fans of her were more than pleased to see her get her own game and hope for more in the future.
* EvilIsSexy: The young James Marcus seems to have been invented for the sole purpose of adding more {{bishonen}} to the series.
* FanonDiscontinuity: Fans who don't like ''[[VideoGame/ResidentEvilGunSurvivor Resident Evil: Survivor]]'' have been known to use the aforementioned ContinuityNod to declare ''Resident Evil 0'' non-canon.
* GoddamnedBats: Actual bats, too!
* {{Narm}}: It's ''Resident Evil''. [[Narm/ResidentEvil What did you expect?]]
* NintendoHard: On Hard, this is comparable to ''ResidentEvilCodeVeronica'' as the overall lack of ammo and healing items is among the stingiest in the entire series. Unlike that game, however, you do not have a decent knife to help conserve ammo, so you must make every shot count, avoid enemies when possible and only heal when absolutely necessary. If you don't have an excess of ammo for your best weapons and healing items for the final boss battle... [[UnwinnableByDesign forget it]]. Have fun starting the entire game over!
* ScrappyMechanic: The inventory system often means having to ferry stuff you need from one area to the other.
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