The story starts off showing a master of the renowned Snake Style fighting and dying at the hands of a wandering Arrogant Kung-Fu Guy, a master of the Eagle Claw who has sworn to kill all masters of the Snake Style.
Then we meet Chien, an orphan regularly beaten upon and treated like a servant by the Kung Fu school that has adopted him. One day after a particular painful beating he sullenly walks along to find an old man set upon by a gang of kung fu fighters. Jumping to his aid and through a series of kung fu hijinks the old man decides to teach Chien the Snake Style and through Training from Hell leads him to his I Know Karate moment.
But the master of the Eagle Claw takes notice of his newfound abilities, and things won't end peacefully...
A definitive Kung Fu classic, here Jackie Chan first departed from the Bruceploitation characters he often portrayed into the comedic action roles he is now renowned for.
This film provides examples of:
- Big Bad: Lord Sheng Kuan, grandmaster of the Eagle Claw school.
- Bluff the Imposter: When Chien Fu first encounters Sheng Kuan, the latter claims to be the Old Man's colleague/brother. Chien calls his bluff, only for the Eagle Claw master to demonstrate Snake Fist techniques, successfully fooling him for now.
- Comforting Comforter: The Old Man does this for Chien, who is the whipping boy for the martial arts school where he's been raised.
- Cool Old Guy: After seeing Chien Fu getting abused yet again, the Old Man cheers him up by playing a game of Keep Away while also teaching him Snake Style footwork.
- Curb-Stomp Battle: Most of the fights the Eagle Claw Master takes part in have him taking his opponents apart, aside from the final battle.
- The Three Provinces Champion defeats the two stand-in masters of Hungtai with pathetic ease. Master Hung fights him to defend Hungtai School's honor, but is still outmatched. Then Chien steps in and takes down the champion himself.
- Does Not Like Spam: The Old Man doesn't drink hot tea. This saves his life when an Eagle Claw spy poisons a hot tea about to be served to him but Chien throws it out.
- Don't Call Me "Sir": The Old Man tells Chien not to call him "Master" since they are friends (in actuality, to keep him out of the Snake-Eagle conflict).
- Fighting Fingerprint: Sheng Kuan realizes Chien is the Old Man's student after seeing him fight with the Snake Fist. He then pretends to be the Old Man's colleague, but while sparring with Chien, he uses Eagle Claw moves which are clearly different. When Chien points this out, Sheng Kuan bluffs that the Old Man didn't teach Chien everything he knows.
- Groin Attack: "Finding the Snake", a move Chien uses on the Mantis School's master.
- And later, "Snake Taking the Pearl" which Chien uses to defeat the Russian fighter.
- Ironic Echo: When Chien Fu warns Master Hung about the Three Provinces Champion, Hung sternly orders Chien to "get back", probably thinking the well-meaning kid is still useless backup. Once Chien starts demonstrating Snake Fist Style and kicking the Champion's ass, Hung steps forward to get a word in and Chien orders him to "get back".
- I Owe You My Life: Chien Fu saves the Old Man's life after he is ambushed and wounded by Eagle Claw disciples. In gratitude, the Old Man teaches him the Snake Fist.
- Nice Job Breaking It, Hero!: Chien Fu inadvertently reveals the Old Man must be hiding nearby after the Eagle Claw master spies on him fighting the Three Provinces Champion using the Snake Fist.
- Nice Job Fixing It, Villain!: After Sheng Kuan fights Chien and leaves him alive to lure out the Old Man, Chien is inspired to invent his Cat's Claw style partially based on Eagle Claw techniques, eventually using it to overcome Sheng Kuan.
- Obfuscating Stupidity: The Old Man pretends to be a grubby beggar to throw off his Eagle Claw pursuers.
- The Funny Foreigner missionary turns out to be a Russian mercenary for the Eagle Claw school.
- Old Master: The Old Man aka Pai Cheng-Tien, grandmaster of the Snake Fist.
- Paper Tiger: The two stand-in masters at Chien's kung fu school who use him as their punching bag. When faced with a challenge by the Three Provinces Champion, they try to chicken out before fighting him two-on-one and they still get their asses kicked.
- Re-Release Soundtrack: The first Jackie Chan film to start the long trend of films featuring him to be re-scored for international audiences. The original Hong Kong release used needledropped music from sources as disparate as Star Wars, The Spy Who Loved Me, and the disco song Magic Fly by Space. For the film's wider international release in the 1980s, a new copyright-friendly score was commissioned. Both scores for the English dub are available on home video.
- Rival Dojos: The overarching conflict is the deadly feud between the Snake Fist and Eagle Claw schools. By the start of the film, Eagle Claw has exterminated almost everyone from Snake Fist.
- A subplot involves the rivalry between the Hungtai School (where Chien works) and the Hungwei School, whose best student is the champion fighter of 3 provinces. The students of both schools flock towards the one with the stronger fighters.
- The Mole: The cook at Chien Fu's school (and the only one nice to him) is secretly a spy for Eagle Claw. After finding out Chien and the Old Man are Snake Fist practitioners, he attempts to poison their tea.
- Title Drop: At the end of the film. The Old Man suggests that he use it as a name for his new style of Kung Fu.
- Took a Level in Badass: Chien, after learning Snake Style, to the point that he defeats the guy who effortlessly took down the two masters of Chien's school at the same time. He levels up again after developing Cat's Claw, and combining it with his Snake Fist.
- Beating the man who defeated the 2 stand-in masters might not seem impressive, given how obviously and grossly incompetent they are—until you bear in mind that the man who beat them is the champion of a competition from 3 provinces, putting him as one of the best fighters around.
- Training from Hell: Pai Cheng-Tien (the Old Man) would know how best to train a student in Snake Fist Style. Even if the two are good friends, the Old Man refuses to pull his punches for someone he likes. Justified in that he knows that if Chien Fu should ever be discovered to have learned the style, or even be acquainted to someone who knows it, his life would be in mortal danger from practitioners of the Eagle Claw.