Originally, Paramount had conceived the series not as a sequel or for television, but a feature remake of The War of the Worlds (1953) with George A. Romero slated to direct.
In 1953 Earth experienced a War of the Worlds. Common bacteria destroyed the aliens but it didn't kill them. The aliens fell into a state of deep hibernation. Now the aliens have been resurrected more terrifying than before. In 1953 aliens started ...
In one episode, an actor dressed as an alien jumps down from an air duct onto a human. As he jumps, you can see his socks.
Sylvia Van Buren is credited for writing the episode "Epiphany". Two other scripts ("The Walls of Jericho" and "The Good Samaritan") are pen-named under amalgams of her name and that of Clayton Forrester. This was because thee was a writers' strike going on at the time and the writers did not want to be credited.
The animation of the alien hand taking a hold of Earth that opens every episode in the first season is omitted on the DVDs.