The Martian drones were performed by two people back-to-back in one suit. A little person was carried in a sort of backpack on the back of a normal-sized performer. The little person would operate the drone's mouth and smaller arms (as seen when the drones load their weapons) while the full-sized performer made the creature walk and used ski poles to move the longer arms (as seen when the drones "salute" Mrs. McKeltch). The full-sized performer faced the rear of the suit and had to walk backwards so that the creature's knee joints would bend in a "not-human" fashion when it walked. Several actors performed the drones, working in shifts, which meant each performer who did the "walking" for a Martian needed his own custom-made footwear.
When Linda and David are hiding in the boiler room, the police enter and while searching for them the "Globe Head" Martian from the original film can be seen sitting atop a cabinet.
Jimmy Hunt, who played young David MacLean in the original Invaders from Mars (1953) and the police chief in this remake, actually has more than almost a dozen lines, not just one as reported by a reviewer. When he and Officer Keeney go up the hill in search of Mr. Gardner, Hunt's line of "Gee, I haven't been up here since I was a kid" is a playful reference to the similar area of Martian activity that he witnessed as the boy in the 1953 movie.