Sydney Brown (Hall) is a Professional Gambler who finds John Finnegan (Reilly) outside a diner one day, broke and alone. Sydney offers to help John find a way to make some money; John at first resists, thinking Sydney is a Dirty Old Man, but eventually agrees to be helped. Two years later, Sydney has become a Parental Substitute for John, and the two are inseparable. John ends up falling in love with, and marrying, Clementine (Paltrow), a cocktail waitress/prostitute. However, they get into a bad situation that Sydney has to help them out of. To make matters, worse, John's friend Jimmy (Jackson) knows about Sydney's past, and knows just why Sydney has taken John under his wing.
Philip Seymour Hoffman, who would become Anderson's most frequent collaborator before his death, appears in one scene as an obnoxious gambler.
Provides examples of:
- Affectionate Nickname: Clementine calls Sydney "captain", because, as she explains, he looks like a captain on a ship. Sydney accepts this, but he gently chides John when he tries to use it on him.
- The Atoner: Sydney. He killed John's father, and is trying to make it up to him by being a Parental Substitute.
- Blackmail: Played with; Sydney thinks at first Jimmy is trying to do this to him because he helped Clementine and John with their Hostage Situation, but Jimmy doesn't care about that and is actually glad Sydney stepped in to help. No, the real reason Jimmy wants to blackmail Sydney is because Jimmy knows Sydney killed John's father, and John doesn't know.
- Bookends: The movie opens and closes with scenes at the same diner—the sequence beginning with a nearly identical shot of Sydney walking towards the entrance.
- The Cameo: P.T. Anderson's father, Ernie Anderson, who died one year after this movie was released, has a brief cameo as the man standing in front of John when the matches in John's pocket catch fire.
- Casting Gag: Philip Baker Hall's character Sydney is intended to be an expansion of his mob-affiliated character also named Sidney in the film Midnight Run. Director Anderson was fascinated by the character and his desire to know more about who he was led him to write the role. This also, in a way, could be seen as an inter-film example of Ascended Extra.
- Cool Old Guy: Sydney. He is even referred to as such by Jimmy in his "Reason You Suck" Speech, though in a mocking way.
- Deadpan Snarker: Sydney's endlessly one for a witty turn of phrase.
- Epic Tracking Shot: The one in this movie isn't as long as the ones in P.T. Anderson's other movies, but it's still pretty impressive, following Sydney as he walks across a crowded casino floor.
- Everybody Smokes: Everybody. Absolutely everybody.
- Film Noir: The laconic Anti-Hero with a Dark and Troubled Past that threatens to catch up to him, a regular guy drawn into morally...interesting territory by the promises of success, and Clementine is even a mild take on a Femme Fatale.
- Fourth-Date Marriage: Clementine and John have only known each other a couple of months before they get married.
- Hooker with a Heart of Gold: Played with; Clementine is actually warm and gracious towards Sydney and John. However, she's rather adamant about getting paid on the job, which leads to...
- Hostage Situation: John and Clementine end up taking one of her clients hostage when he refuses to pay, and it's up to Sydney to fix things.
- Jump Cut: John initially suspects Sydney might be looking for gay sex, so when he gets in Sydney's car he insists on riding in the back. John admires the car for a little bit and then asks Sydney to pull over, and then there's a Jump Cut to John in the front seat next to Sydney.
- Parental Substitute: As stated above, Sydney becomes this to John. Also, to a lesser extent, to Clementine.
- Production Foreshadowing: When confronting Sydney over his past as an Atlantic City mobster, Jimmy namedrops several of his fellow criminals, including Floyd Gondolli, Jimmy Gator, and "Mumbles" O'Malley. In Paul Thomas Anderson's next two films after Hard Eight, Boogie Nights and Magnolia, Philip Baker Hall's characters are, respectively, Floyd Gondolli and Jimmy Gator.note
- Professional Gambler: Sydney, and he mentors John into one, himself. Jimmy is apparently one, himself.
- "The Reason You Suck" Speech: Jimmy chews Sydney out, explaining that it was perhaps vanity to expect to get away with killing John's father without any repercussions.
- Retired Badass: Sydney. Sydney is whiling away his senior years playing keno and mentoring John, but Jimmy finds out that in the past, Sydney was a real hardass. He does not draw the proper conclusion from this knowledge.
- Scary Black Man: Samuel L. Jackson in his sweet spot. Jimmy wears a leather coat and leather driving gloves which only make him scarier.
- Title Drop: Jimmy refers to seeing Sydney betting on a "hard eight" (two fours) at the craps table, and Sydney also bets on Philip Seymour Hoffman's character making that roll. Near the end of the movie, Jimmy rolls a hard eight and cleans up. (The title was a case of
Executive Meddling, as Anderson wanted to call the film Sydney). - Too Dumb to Live: Jimmy says to the man he’s blackmailing, “I’m not a killer… like you.” He does not consider the implications of that statement.
- You Would Do the Same for Me:I want you to see that my reasons for doing this are not selfish, only this: I'd hope that you would do the same for me.