Continuity mistake: David and Kathy exit to the outside of the building, closing the inside door and the outer door. When Sheriff Carver exits to the outside, the inner door is not closed, but open as he steps out.
Other mistake: The sheriff drives a hard top, solid roof police car yet he wears a motorcycle cop's helmet.
The Leeches - S1-E4
Factual error: When David Vincent lands at the airport, a sign there says, "Welcome to San Diego." When Vincent exits the airport, it says, "Maricopa Airport." There is a Maricopa in California, but the episode takes place in Arizona, as indicated by the license plates on the cars and mentioning the city of Tucson close to the town the episode takes place in.
The Leeches - S1-E4
Other mistake: David Vincent arrives at the airport and a sign says "Welcome to San Diego", but the episode takes place in Arizona and references Arizona-related locales: Tucson, Maricopa County, etc.
Revealing mistake: A chalk outline on the parking garage wall where the actor playing the alien that just got shot and disintegrates is supposed to place his body and limbs for the special effects (the disintegration) is visible. The actor placed his body just outside the chalk outline, and the arms were not in the correct positions.
Other mistake: After being shot in the air traffic controller's office, the alien disintegrates, but the black residue remaining afterwards is out of position from where the alien disintegrated.
Continuity mistake: The dead air traffic controller's body changes position from being splayed out on his desk to sitting upright in his chair when the scenes instantly cut.
Other mistake: The Invaders' computer announces David Vincent has "sandy" hair, but Vincent's driver's license states he has brown hair. His license also says he has brown eyes, but the actor playing him has blue eyes, and the computer says he's 5' 11", even though one of the Invaders entered the 5' 9" info from his license into the computer.
Continuity mistake: The bartender behind Doctor Raynerd changes positions as the camera shots quickly change angles.
Visible crew/equipment: Light reflecting screens are seen in the rear doors of the Midlands Academy van.
Continuity mistake: When Simon Carver and David are speaking in Carver's office, Carver's hands instantly change positions form being spread out on his desk to clasped as the camera shots switch.
Continuity mistake: David Vincent parks his car in front of his hotel and goes up to his room. Later, David's girlfriend, Susan, parks her car in the same space where David's car was parked - he never left his room to move it.
Continuity mistake: As Susan and David kiss, her left hand instantly moves from behind his neck to just below his left shoulder.
Other mistake: In the introduction to this episode, actor Roy Thinnes mistakenly says that the guest actor, Burgess Meredith, played the Joker in the "Batman" TV series. Meredith actually played the Penguin.
