the protagonist is suspected of being a replicant
Clips of meteor strikes on New York and Paris are used as news clips of "alien attacks" in Impostor.
Poster seen in theater lobby
Natalie mentions having seen a movie about an extraterrestrial who didn't know he was an extraterrestrial. Coincidentally, the film she describes stars both Gary Sinise and Tony Shalhoub.
Clips and behind-the-scenes
Impostor is #9.