Jamie Lee Curtis, Charles Cyphers, Kyle Richards, Nancy Stephens, and Nick Castle were in the original Halloween (1978) and they all returned for this sequel. The characters of Tommy Doyle and Lonnie Elam from the original also returned, but were recast with Anthony Michael Hall and Robert Longstreet. Brian Andrews retired from acting in 2015 and Brent Le Page never acted again after the original Halloween.
David Gordon Green recalled that when they attempted to find a yearbook photo of one of Michael Myers' victims from the 1978 film, he came across a yearbook photo of Bob Odenkirk that he thought resembled original actor John Michael Graham. The rights issues were resolved so that Green could use Odenkirk's photo instead of the actual actor. Odenkirk is therefore credited as 'Bob,' despite not physically appearing in it.
Twelve pumpkins are featured in the opening title sequence with the last one indicating Halloween Kills as the twelfth Halloween film.
In the flashback scene to 1978, Michael attacks deputy McCabe (Jim Cummings) with a rope. In the original Halloween (1978), Sheriff Leigh Brackett (Charles Cyphers) responded to an alarm in a hardware store, and reported that a rope, some Halloween masks and a set of knives were stolen.
Early in the movie, the wagon stolen by Michael Myers from Dr. Loomis and Nurse Marion Chambers at the Smith Grove Sanitarium in Halloween (1978) can be seen parked behind Young Hawkins and Pete McCabe during one of the flashback sequences to 1978.