Go to ABC.com, click on free episodes, choose Lost, pick episode 15 of season 5. Skip, or watch until 15 minutes and 46 seconds.

When Sawyer grabs the pistol from the desk after he hears a knock on the door. Notice that it is an M9 Beretta. Since they are in 1977 the Beretta still wasn't even made yet! The Beretta was developed in the 80s and brought to service in the 90s