When Mack is dragged off after their performance, Sam chases after him and throws a punch at one of the henchmen who falls backward. Sam's punch can clearly be seen hitting nothing but air.
While Sam, Mack, and Frankie are driving to New Mexico, there is a 50-star American flag seen hanging by the driver seat. The episode takes place April 30-May 2, 1959. Hawaii hadn't been admitted as a state yet (Aug 21, 1959), and while Alaska had been admitted (Jan 3), its star wouldn't be added to the flag until July 4, so the flag would have been a 48-star flag.
One of the most prominent bits on the show was in regards to Superman, Supergirl and a man on the street interviewer. The leap takes place on April 30, 1959, Supergirl would not debut until May of 1959, so no one would know who she was.