* CowboyBebopAtHisComputer: One of the trivia questions in the second game is to name which alien race the X-Men have never encountered. The in-game answer? Skrulls. This is in spite of the fact that at the time the game came out, there had already been ''two'' arcs where the X-Men had encountered the shape-shifting race[[note]]The first running through ''Uncanny X-Men'' #275-277 and the second going through ''Uncanny X-Men'' #368-370 and ''X-Men'' #88-90[[/note]].
* HeyItsThatVoice:
** Creator/PatrickStewart reprises his role from the [[Film/{{X-Men}} movies]] as Professor Xavier.
** Likewise, RobinAtkinDownes reprises his role from ''VideoGame/XMenNextDimension'' as Pyro and takes on the role of Cyclops in the first game (while absent in the second game, he'd later reprise the role of Cyclops in the first ''MarvelUltimateAlliance'' game).
** This series would also be the first time Creator/SteveBlum and Peter Lurie voiced their respective roles of {{Wolverine}} and Sabretooth, with both reprising their roles in ''MarvelUltimateAlliance'', ''WesternAnimation/WolverineAndTheXMen'' and ''WesternAnimation/{{Ultimate Spider-Man}}'' and Steve as Wolverine [[WesternAnimation/AvengersEarthsMightiestHeroes a]] [[HulkVS lot]] [[VideoGame/SpiderManWebOfShadows of]] [[TheSuperHeroSquadShow times]] [[MarvelVsCapcom3 since]]. Steve also voiced Omega Red in the second game and Peter voiced Avalanche in the first game, and [[ComicBook/AgeOfApocalypse Holocaust]] and [[TheOtherDarrin Blob]] in the second one.
** Creator/CreeSummer is Magma; while she herself wasn't in any prior incarnations of X-Men, her father, Don Francks, voiced Sabretooth in the 90s ''WesternAnimation/{{X-Men}}'' animated series.
** Creator/JohnDiMaggio is Juggernaut.
** Creator/JenniferHale is Scarlet Witch and the Stepford Cuckoos.
** Creator/JoshKeaton is Cyclops [[TheOtherDarrin in the second game]].
** Creator/EdwardAsner is Healer.
** Lou Diamond Phillips ([[StandAndDeliver Angel Guzman]]) is Forge.
** Creator/TaraStrong is Blink.
** Creator/TonyJay is Magneto in the first game.
*** Richard Green ([[WesternAnimation/TheBatman Hugo Strange]], [[WesternAnimation/TransformersPrime Skyquake]]) is Magneto in [[TheOtherDarrin in the second game]].
** John Kassir ([[TalesFromTheCrypt The Crpyt Keeper]]) is SelfDemonstrating/{{Deadpool}}, Pyro ([[TheOtherDarrin in the second game]]), and Sauron.
** Creator/KharyPayton is Bishop and Nick Fury.
** Creator/JamesArnoldTaylor is Iceman [[TheOtherDarrin in the second game]].
** Music/GreyDeLisle is Mystique.
** Dawnn Lewis ([[Series/ADifferentWorld Jaleesa Vinson-Taylor]], [[HanginWithMrCooper Robin Dumars]], [[WesternAnimation/SpiderManTheAnimatedSeries Terri Lee]]) is Storm [[TheOtherDarrin in the second game]].
** Danica [=McKellar=] ([[TheWonderYears Winnie Cooper]], [[StaticShock Frieda Goren]], [[WesternAnimation/YoungJustice Miss Martian]]) is Jubilee.
** Earl Boen ([[Franchise/{{Terminator}} Dr. Silberman]], [[VideoGame/MonkeyIsland the ghost pirate LeChuck]]) is Colossus in the first game.
*** Creator/JimWard is Colossus [[TheOtherDarrin in the second game]] and [[ComicBook/AlphaFlight Guardian]].
** Creator/DeeBradleyBaker is Nightcrawler and Multiple Man.
** Richard [=McGonagle=] ([[WesternAnimation/{{Ben10}} Four-Arms]], [[WesternAnimation/Ben10AlienForce some of the Highbreed]], [[WesternAnimation/StarWarsCloneWars General Grievous]]) is Apocalypse in the second game.
** Alastair Duncan ([[WesternAnimation/TheBatman Alfred Pennyworth]], [[LegacyOfKain Mortanius]], [[Franchise/MassEffect Councilor Sparatus]]) is Bastion.
** Masasa Moyo ([[CelebrityDeathmatch Tally Wong]], [[JadeEmpire Silk Fox]], [[JediStarfighter Adi Gallia]]) is Psylocke in the first game and Shanna The She-Devil in the second.
** Dorian Harewood ([[WesternAnimation/IronMan War Machine]], [[WesternAnimation/MegasXLR Ender]], [[WesternAnimation/TheBatman Martian Manhunter]]) is the Shadow King.
** Armin Shimerman ([[WesternAnimation/EvilConCarne General Skarr]], [[Series/StarTrekDeepSpaceNine Quark]], [[Series/BuffyTheVampireSlayer Principal Snyder]], [[VideoGame/BioShock1 Andrew Ryan]]) is Toad.
** Catherine Taber ([[VideoGame/KnightsOfTheOldRepublic Mission Vao]], [[WesternAnimation/StarWarsTheCloneWars Padmé]], [[VideoGame/TheForceUnleashed Leia]], [[VideoGame/FinalFantasyXII Penelo]]) is Rogue in the second game.
** Keith Ferguson ([[Franchise/KingdomHearts Marluxia]]) is Grizzly in the second game.
** Creator/KimMaiGuest is Lady Deathstrike and Shadowcat in the second game.
** Creator/QuintonFlynn is Banshee and Abyss.
** Creator/DwightSchultz is Garokk and the Living Monolith.
** Creator/DaveWittenberg is Archangel.
** Daniel Riordan ([[Anime/TransformersRobotsInDisguise Megatron]]) is Mr. Sinister and Stryfe.
* WhatCouldHaveBeen: DummiedOut content in the PC version of the second game indicated that Dazzler was planned as a playable character at some point.