Depending on the affiliation of the active character and the NPC to whom they're talking, their response will be different: friendly if both characters are X-Men or Brotherhood members, and hostile if it's an X-Man speaking to a Brotherhood member or vice versa.
Beginning in this game, Iceman no longer wears a bandana on his head which makes him look like his Uncanny X-Men design and less like the Ultimate X-Men design seen in X-Men Legends (2004). However, Iceman continues to wear an armband on his left bicep, only this time it's a black armband instead of navy blue.
In the New York City levels, some of the destroyed buses have a "Raven" sign on their sides and raven logos. This is a reference to Raven Software, the company who developed this game, along with its predecessor X-Men Legends (2004).
In the Weapon X facility, one of the rooms has a Newton's cradle on a table. This may be a reference to X-Men (2000) where Magneto had a Newton's cradle in his hideout, and he used his powers to get them moving.
The developers intended the game to have a greater sense of scale than its predecessor, X-Men Legends (2004), with a story where the X-Men would need to ally themselves with the villains known as the Brotherhood of Mutants to defeat a greater threat, the mutant supervillain Apocalypse and his minions.