According to the DVD documentary, included in the final cut of the film, is a scene where Al Pacino's character gets rudely bumped into on 5th Avenue, while trying to court Ellen Barkin's character. According to Director Harold Becker, this was an unscripted moment caused by a real New Yorker, and not an extra. Pacino incorporates the moment into his performance, and continues without missing a beat.
There are two renditions of the 1950s song "Sea of Love" heard in the movie. This included the original 1959 recording performed by Phil Phillips with the Twilights and a then new 1980s end title version performed by Tom Waits.
Ellen Barkin, in a 2011 interview with Chicago's Huffington Post, said that this movie was not her best work, didn't think Director Harold Becker liked her, but this movie did make her a household name. The article states that Barkin says that "she was forced into doing the sensual grocery store scene, where she caresses yellow peppers while wearing little under her raincoat other than a sly thigh to entice co-star Al Pacino. Barkin said she had a big fight with Becker over it, since she really didn't want to do it. Pacino was 'brilliant' and 'very generous' to work with, but the reason it's hard for her to watch, is when she views Sea of Love (1989) what the audience sees as 'attitude' on her part, is really a 'tenseness'. But through her training in method acting at the Actors Studio, she made her tenseness in that scene work for her in front of the camera. It was her first role where she was cast as 'an object of desire'."
When Frank Keller is trying to convince his Lieutenant to let him try the restaurant sting operation without wearing a wire, he says "What is she gonna do, confess? Shoot me? We're in a restaurant!!" Al Pacino famously played Michael Corleone in a scene where he shot a cop in a restaurant, which was also supposed to be improbable.
In addition to the deleted scenes from the DVD, and the Lorraine Bracco scenes from the television premiere, the theatrical trailer features a glimpse at yet another scene not in the final cut. In it, a guy recognizes Keller and draws a gun on him, to which Keller does the same and says "Don't you move!"
The scene where Al Pacino and John Goodman are undercover in a restaurant, was filmed in New York City restaurant O'Neal's. Located at 49 West 64th Street in Manhattan (near Lincoln Center), and owned by actor Patrick O'Neal for many years, the restaurant closed in 1993, not long before O'Neal's death in 1994.
The interiors and soundstage set sequences, for this New York City-set movie, were filmed in Toronto, instead of the Big Apple. The exteriors were still shot in New York City, with most of them being filmed in the city's Upper West Side.
The Lonely Hearts advertisement in the singles magazine, that the NYPD took out, was a poem by Frank Keller, Jr.'s (Al Pacino's) mother, written in 1934 while she was in high school. The ad read: "Lady - I live alone within myself like a hut within the woods. I keep my heart high upon a shelf barren of other goods. I need another's touch and smile to fill my hut with songs. I remain; a single, white, male, 42. NYW POB 233".
This New York City-set picture, filmed its location exteriors there, featured such locales in Queens, The Bronx, Broadway in the 70s, the Taft House in East Harlem, Eighth Avenue, O'Neal's Balloon near the Lincoln Center, East 57th Street, West End Avenue, West 84th Street, Amsterdam Avenue, and the 59th Street Bridge.
Due to interiors being shot in Toronto, and exteriors being filmed in New York City, much attention to detail needed to be made for continuity, to make sure that portions of shots relating to the same sequences matched.
One of two late 1980s Hollywood thrillers with a title based on a famous song. The other was Someone to Watch Over Me (1987). Both movies were set in New York City, and both prominently feature their famous tunes.
The movie's title is derived from the classic 1950s song of the same "Sea of Love" name. According to Wikipedia, the 1959 tune was the subject of this movie and was "written by John Phillip Baptiste (a.k.a. Phil Phillips) and George Khoury. Phillips' 1959 recording of the song peaked at number 1 on the U.S. Billboard R&B chart, and number 2 on the Billboard Hot 100". The cover, made by The Honeydrippers, reached number 3 on the Billboard Hot 100 chart in 1985.
The meaning and relevance of this movie's "Sea of Love" title refers to the pool of murdered male victims, that have resulted from a series of one night stands, derived from Lonely Hearts advertisements in a New York City singles magazine.