Don't Bug the Mosquitoes - S2-E12
Other mistake: The 4 band members, all their equipment, months worth of food supplies, I am assuming medical supplies, change of clothes and other sundry items all magically fit into a small two seat helicopter.
Other mistake: Although Diane Murphy played "Annabelle", she is listed in the closing credits as having played "Diane". (00:25:00)
Other mistake: As Virgil prepares to clear the wreckage of the tower from the rescue area using the Firefly, Scott tells him that he will go over to Thunderbird 2 to prepare the Mole for tunneling. The Tower Controller then says to Scott, "I've got a fast car ready for you outside" without moving his lips.
Come Back, Little Googie - S1-E25
Other mistake: When Eddie's naughty little friend goes to shake hands with Herman they insert a quick close up of a hand buzzer in his hand, only it's obviously an adult's wrinkly hand.
The Addams Family and the Spaceman - S1-E27
Other mistake: In this episode, the radio announcer said that the reported spacecraft was seen over the Cemetery Ridge District, and Morticia said "That's our area." However, in "Cousin It Visits The Addams Family" (S1: Ep 20) they are supposedly in the Greenbriar Woodlawn District.