This marks the first time in which Oscar carries a weapon. It is a small snub nose revolver, possibly a .38.
Jane merrow (lrina leonova) previously appeared in season 1: episode 6 doomsday and counting
John De Lancie appears in an uncredited role as a soldier. Both parts 1and 2.
The Death Probe was later redressed and used as the Crimebuster in Heartbeeps 1981.
When the Russians are tracking the object, the computer shows the coordinates of "LONGITUDE 44 DEGREES 10 MINUTES LATITUDE 108 DEGREES 21 MINUTES", and she states that it was in Wyoming. First of all, 108 is not a valid latitude. Second, the town of Ten Sleep, Wyoming is, in fact, at LATITUDE 44.1 LONGITUDE -108.21, so it could simply be that perhaps the Lat/Long numbers are just swapped (and missing the minus sign on longitude).