The first chapters of the game are a deliberate homage to Black Hawk Down, by the director's admission. They saw that movie and thought they could make a pretty good horror game out of it.
Barry Burton's lines in The Mercenaries: Reunion are his old narmful lines from the original campy Resident Evil, as well as having "HERE'S Barry!" (to address RE1 Jill's question of his whereabouts) and a melee attack called... Barry Sandwich.
Wesker throws his shades at Chris before delivering a powerful series of attacks. This is a shot-for-shot recreation of an identical scene from the Mark Dacascos film Drive, as seen here.
They also have two villains who share the same name...albeit spelled differently (Riccardo vs Ricardo) and with completely different motivations. One wants to gain eternal life by impregnating the main character, the other wants to make a lot of money.
Chris' "Warrior" costume is a homage to Mad Max. Complete with sawed-off shotgun!