As one of Hollywood's longest-running horror franchises, Halloween has a legacy that extends far beyond one legendary original film. Regardless, John Carpenter's 1978 classic has achieved a reputation that invites references and homages, including from some of its own franchise's later installments.

RELATED: 10 Best Movies Inspired By The Work Of John Carpenter

Redditors have noticed some that may not be caught by most viewers on their first watch. It stands to reason that David Gordon Green's Halloween Ends will add to the number of existing references, considering how much reverence his two other films had for Carpenter's original.

The Cenobite - Halloween H20 (1998)

Nurse Marion in Halloween.

RCGBlade started a thread to point out a subtle franchise crossover in Halloween H20: "In the beginning scenes of Halloween H20: 20 Years Later (1998), a Cenobite from the Hellraiser franchise can be seen as a Halloween decoration in the background.

There are also many references to Carpenter's original film and Rick Rosenthal's Halloween II in H20's opening credits. The camera pans past newspaper clippings and other documentation of the Myers case, all of which reference specific events of Myers's night of terror. Furthermore, the opening scene takes place in the home of Nurse Marion Chambers, who is again portrayed by Nancy Stephens.

Janet Leigh As Norma - Halloween H20 (1998)

Janet Leigh with Ford Sedan in Halloween H20

Numerous-Lemon started a thread to point out some subtle details in Steve Miner's Halloween H20: 20 Years Later. "In Halloween H20, Norma is played by Janet Leigh, who played Marion in Psycho. She also owns the same car as Marion," they say.

Not only did Leigh star as Marion Crane in Alfred Hitchcock's seminal Psycho, but she's also Laurie Strode actress Jamie Lee Curtis's real-life mother. Like in Carpenter's excellent early-'80s movie The Fog, their shared scenes are a treat for nostalgia-loving horror aficionados.

I Guess Everyone's Entitled To One Good Scare - Halloween H20 (1998)

Laurie discovers Michael is back in Halloween H20

Hyrule_Hyahed added to the reverence displayed in Leigh's H20 scenes: "And Janet quotes the Sheriff from Halloween (1978) when she scares Jamie 'I guess everyone's entitled to one good scare.'"

RELATED: Michael Myers's 10 Strongest Enemies, Ranked

This was a line spoken by Sheriff Leigh Brackett in the original movie, and it's interesting to imagine what's going through Strode's head as she hears it two decades later from a different source. H20 went a similar route to the one Green's films would take yet another 20 years later, and some of its callbacks proved equally effective.

The Needle Hole In Michael's Mask - Halloween (2018)

Halloween 2018 Michael Myers Out At Night with kids behind him

Strode's final confrontation with Myers is one of the major things fans want to see in Halloween Ends. They have seen several variations of the same conflict, but this will be the ultimate conclusion to what was started while she was babysitting in 1978. On that night, she managed to get several good shots in on Myers, including with a knitting needle.

One Redditor started a thread to point out the wound on the back left of Myers's neck, which can be seen when Myers looks to his right. The post, titled "Details," simply shows an image of Myers with the knitting needle in his neck in the 1978 film as well as an image from Myers's 2018 neighborhood rampage.

The One Shot - Halloween (2018)

Michael Myers rises in 2018's Halloween.

Halloween (2018) wore its appreciation for Carpenter's original film on its sleeve, mostly via continuity-based character details. However, it also referenced key moments in the original as well, including several of Myers's most shocking kills.

Dexter07 wrote about all the little things they enjoyed in Green's film: "Really loved all the little throwbacks they added in this movie. Laurie poking out from the shadows (the Shape in the first one), knife kill on the wall, and the sheet ghost. The one-shot take was really well done."

Teacher Lynda - Halloween (2018)

Laurie Strode prepares for Michael's arrival in Halloween (2018)

It's blink-and-you'll-miss-it, but Curtis isn't the only cast member from Carpenter's original to reprise her role in Halloween (2018). Lynda Van der Klok actress P.J. Soles makes an appearance early in the movie as Allyson Nelson's teacher. It's a fun little moment that further shows the new trilogy's love for the classic original.

RELATED: All Returning Legacy Characters In Halloween Kills

Lineman72T brought up the cameo, writing "The teacher in this was played by P.J. Soles, who played Lynda in the original."

Michael's Eye - Halloween Kills (2021)

Michael Myers looking out the window in Halloween Kills

Myers is the ultimate slasher villain if only for how plausible he is. In the original movie, he's a man with a pulse, a knife, and a mask. The 2018 sequel presumably kept his mortal status, which was more or less lost by Halloween 4: The Return of Michael Myers. However, with all he survives in Halloween Kills, it seems that he may be immortal after all. Myers is frequently seen maskless in that movie, which reveals not just his burns from Strode's basement in 2018, but also his eye, which has been blinded ever since she stabbed him with a coat hanger in 1978.

JossRedHood wrote of Myers's appearance in Halloween Kills: "Michael is also blind in the eye Laurie stabbed him in in the '78 film. It's the little details that are amazing."

Karen's Christmas Sweater - Halloween Kills (2021)

Judy Greer's Karen holding Michael's mask

Karen Nelson ends up losing her life on the very day she hates. As a cheeky and interesting character detail, Nelson wears a Christmas sweater throughout Halloween Kills's finale. It's a personal stance against a day that saw her mother's life severely damaged and, now, has taken her husband as well.

TravTheScumbag put it succinctly with: "Karen wears the Christmas Sweater as an F You to Halloween." It's a more subtle reaction to the pain than her mother's, which was to build an armory.

NEXT: 10 Scariest Scenes From The Halloween Franchise, Ranked