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When speaking in a interview shortly after the film's release, directors Kevin Kölsch and Dennis Widmyer talked about a lot of material that was cut from Pet Sematary's final cut. Amidst remarks about deleted content that fleshed out the relationships between Louis and Jud, as well as Louis and his daughter Ellie, an entire alternate ending was shot for the film; an ending that, according to Dennis Widmyer's remarks below, was pretty hard to cut: "That [alternate] ending we shot first, and then we decided, you know, to have this other ending, so the studio could test two different endings we [edited] them both and both endings [test] scored pretty equally. They're both disturbing and dark. [But] I would say that the current ending [in the final film] sends off the audience with a smile on its face, while at the same time though, [they're saying] 'That was messed up!' Whereas the other one, I don't think anyone would be smiling. The other one has more of a bleak, kind of sad tone to it."
During Ellie's birthday party, Jud can be heard in the background saying, "There was a big Saint Bernard... killed four people". This is an obvious reference to Cujo (1983), another movie based on a Stephen King novel.
When Rachel is returning home from Boston, there is a highway sign that says "Derry 20 miles". Derry is a town that appears in numerous Stephen King stories, most prominently in "IT."
Animal trainer Melissa Millett revealed that a total of five cats, all rescues, were cast to play Church, although ultimately one of them dropped out after getting scared on the set. The feline actors were accommodated in five trailers, along with their human trainers, although one had to be kept in a separate trailer from the others because it did not get along with its cast mates. Millett noted, "The only good working cat is a happy cat...They were quite spoiled." The film crew even built an area near the trailers, nicknamed a "catio," where the hard-working kitties could play and relax between takes. The cats spent two months in training for the shoot, which took around 10 weeks. Aside from the one cranky cat, the rest reportedly got along well with each other and with the movie's human stars, including Jason Clarke and John Lithgow. The quintet of feline stars all found homes after the shoot was done: two were adopted by the movie's animal coordinator, Millett found homes for another two with friends, and kept one herself.
Referring to the original adaptation Pet Sematary (1989), Stephen King has stated that of all his novels, this is the only one that genuinely scared him.
According to an article in The Hollywood Reporter in October 2019, Paramount reportedly decided to push forward with a remake when they received a termination notice from Stephen King for their rights to the book.