Happy Birthday, Milla!
When they are breaking the first code on the security door to the Red Queen's main room,
the security code ends up being:
12 being December
12-17 being December 17th,
12-17-7 and since there are 5 digits in this code it ends up being
12-17-7|5| aka December 17th 1975 -- Milla's Birthday!
Producer Makes a Cameo, Three Times!
One of the producers of the film, Jeremy Bolt, appears numerous (3) times in the film as a zombie. When the cast first encounters the zombies, he is seen being shot two different times. When they open the securiy doors and zombies pull J.D. in, the camera goes to a closeup of a zombie biting Michelle Rodriguez's arm, thats him as well.
Director's Sister Gets a Cameo
Paul Anderson's real life sister makes a cameo in the movie as a zombie/person. She is the woman who works in the lab where the virus is spilled at the begining of the movie. She appears again towards the end of the movie in the same room but she is now a zombie.