In one episode a bus full of convicts on route to play a hockey game pick up a couple of hitchhikers who were possessed by Martians. As was want in the series the possessed hitchhikers died and the Martians possessed two convicts. also as want, when humans died after possessed, they kind of melted to a puddle. For one thing it is odd that a convict bus would pick up hitchhikers and another no one noticed the hitchhikers were gone.
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.
Throughout the entire first season, the aliens are preoccupied with finding their hibernating comrades, and only twice do they ever discuss getting a hold of the original warships from the 1953 invasion. However, Dr. Harrison Blackwood says in the pilot episode that there were thousands of ships warehoused by the military after the invasion, and it would only take the aliens getting a hold of one of them to wipe out humanity. It seems odd then that the aliens never make this a priority.