On some levels you can find XPS-themed monitors, CPU cases and laptops manufactured by Dell, which might be an in-game advertising.
In the subway levels, several places have subway maps present, probably to increase the sense of realism in the game. However, these maps are actually parts of the real New York City Metro subway maps. This is most likely an easter egg, since the events of F.E.A.R. take place in a fictional and seemingly west-coast city. Add