Throughout the series, many objects are incinerated along with aliens who burn up as they die. This episode has the first of only two instances when a burning alien starts an actual, ordinary fire by his death.
When Ceilia Baxter (Janet McLachlan) looks in the drawer where her husband took his gun from the paper in it is an actor's contract form. The wording could be seen when the camera panned in on it.
This is the episode that establishes the difference between black humans and black Invaders in that the black Invaders' palms are the same complexion as the rest their skin.
Roscoe Lee Browne, Raymond St. Jacques and D'Urville Martin all appeared in this episode. Three years earlier in 1964 they all also appeared together in the movie "Black Like Me".