The film features an ensemble cast consisting of Gael García Bernal, Vicky Krieps, Rufus Sewell, Alex Wolff, Thomasin McKenzie, Abbey Lee, Nikki Amuka-Bird, Ken Leung, Eliza Scanlen, Aaron Pierre, Embeth Davidtz, and Emun Elliott.

The next morning, the manager invites the family to a secluded beach where three additional parties are present: rapper Brendan "Mid-Sized Sedan" and his female companion; surgeon Charles, his elderly mother Agnes, his wife Chrystal, and their young daughter Kara; as well as Jarin and Patricia Carmichael, a close-knit husband and wife.

As the day progresses, Jarin drowns, Kara falls to her death, and Patricia suffers a fatal epileptic seizure.

Trent and Maddox discover the notebook of a previous traveler filled with names of many people who died on the beach, along with indications of their being watched.

Chrystal's hypocalcemia results in her bones repeatedly rupturing and improperly healing, gruesomely contorting her body and eventually killing her.

The researchers lure a new group to the beach, but are interrupted by Trent and Maddox, who survived their underwater swim, using the notebook as evidence that they give to vacationing police officer Greg Mitchel.

Additional cast members include Kathleen Chalfant as Agnes, Charles' mother; Gustaf Hammarsten as the resort manager who heads the secret research team for the pharmaceutical company Warren & Warren; Francesca Eastwood and Matthew Shear as resort employees; Kailen Jude as the manager's nephew Idlib; Daniel Ison as vacationing police officer Greg Mitchel; and M. Night Shyamalan as the resort employee who drives the guests to the beach and monitors them.

"[4] In September 2019, Universal Pictures announced its plans to distribute two then-untitled independently financed thriller films written and directed by M. Night Shyamalan.

"[5] In May 2020, Eliza Scanlen, Thomasin McKenzie, Aaron Pierre, Alex Wolff, and Vicky Krieps entered negotiations to star.

[11][12] On September 26, 2020, principal photography began in the Dominican Republic, and to celebrate, Shyamalan revealed the film's title and published its first promotional release poster.

[20] Old was inspired by films created during the Australian New Wave, including Walkabout (1971) and Picnic at Hanging Rock (1975), along with The Exterminating Angel (1962), Kuroneko (1968), Jaws (1975), and The Twilight Zone.

[21] To create a claustrophobic feeling, Shyamalan employed several filming techniques from Akira Kurosawa's Rashomon (1950) and Ran (1985).

[23][24] To capture footage of the surrounding nature, Shyamalan's daughter, Ishana, served as the film's second unit director.

[25] His other daughter, Saleka Shyamalan, wrote an original song for the film titled "Remain" that was inspired by the topic of marriage vows and U2's "With or Without You," used to "highlight the relationship between Guy and Prisca and the love that exists between them.

"[25] Wolff said he and McKenzie were the first actors to be cast after submitting audition tapes, and recalled passing out during the filming of the pregnancy scene due to high temperatures.

[36] A premiere for the film was held at Jazz at Lincoln Center in New York City on July 19, 2021, which was attended by its cast and crew.

[37][38] Anthony D'Alessandro from Deadline Hollywood said the teaser reminded him of a two-part episode of The Brady Bunch, where an ancient tiki brings the group bad luck and causes Greg (Barry Williams) to suffer a surfing accident.

[43] Summarizing the film's marketing results, RelishMix wrote that it was being compared to A Quiet Place Part II and The Conjuring 3, Shyamalan's Split and Glass, and Edgar Wright's Last Night in Soho, as well as ABC's Lost.

According to Universal Pictures, the Super Bowl teaser was viewed at least 100 million times, but overall, videos promoting the film "[fell] short of the norm along with daily click-rates.

"[44] A Snapchat aging filter created for the film also gained 23 million views worldwide on its first day after it was used by celebrities such as Shaquille O'Neal, Kenny Smith, and Charles Barkley.

With audiences that were 52% female and 62% at or over the age of 25, it went on to debut to $16.85 million,[50] making it the sixth film of Shyamalan's to top the box office, though it marked the lowest opening weekend of his career.

[44][51] Describing the openings of Old and Snake Eyes as "weak," Michael Cieply wrote an analysis to explain the audience decline at the box office, streaming sites, and television by using Occam's razor, "Maybe, as a group, we are suffering from 'screen fatigue' — not in the narrow sense of migraines, eye strain, and Computer Vision Syndrome, but in a much bigger way, as a culture.

The website's consensus reads: "Old has no shortage of interesting ideas -- and writer-director M. Night Shyamalan's uneven execution will intrigue or annoy viewers, with little middle ground between.

"[68] WXIX-TV's Terrence "TT" Todd gave a similar response and said that while the premise was interesting, the plot was confusing and could have been explained better as its own television series.

[69] From Vox, Alissa Wilkinson wrote that "Shyamalan has not grown any more skilled at writing dialogue over the years," but found that at its best, the film was comparable to Luis Buñuel's The Exterminating Angel.

[70] Barry Hertz of The Globe and Mail said that the film had "stilted dialogue that runs in circles, dumb-dumb plot holes, [and] a bizarre determination to have his performers act as unnaturally as possible.

"[70] From ABC News, Peter Travers said he was "shocked" to find "how clumsily [Shyamalan] handles potent themes about sudden death and the collapse of time that should resonate powerfully in the COVID-19 era.