Penniless but plucky acrobat Jiang (Jackie Chan) struggles through various schemes to earn himself a buck. When he stumbles upon two martial arts masters engaged in a woodland duel that proves fatal for one, Jiang takes the body into town to collect the reward. Uncle Beggar (Lee Man-Tai), a closet kung fu master, sees through Jiang's efforts to pass himself off as a legendary hero. He offers to train Jiang in kung if he in turn helps a heroic father (Lee Hae-Ryong) and daughter (Doris Lung Chun-Erh) duo safeguard not one but two martial arts Macguffins: the "Evergreen Jade" and the "Soul Pills." This seems easy for Jiang since he fancies the pretty daughter. Complicating matters however is a traitor in their midst along with three different evil groups plotting an ambush: snake-wielding witch Lady Mui (Julie Lee Chi-Lun), the notorious Iron Hand Lui and The Man with a Thousand Faces. Somehow bumbling Jiang has to get super-skilled, super-fast in order to save the day.
Jackie Chan's first attempt at a kung fu comedy was made while the then-struggling actor was still under the stranglehold of producer Lo Wei. Lo's efforts to launch Jackie as the next Bruce Lee, via "grim avenger" type vehicles like New Fist of Fury (1976) and To Kill with Intrigue (1977), were going nowhere so he uncharacteristically gave the star free rein to try something, frankly anything else. Re-teaming with director Chen Chi Hwa after the sober but still solid Snake and Crane Arts of Shaolin (1978) was an unfortunate box-office failure, Jackie penned the script for Half a Loaf of Kung Fu himself. The result was a provocative parody of then-prevailing tropes in martial arts cinema; a scattershot farce cocking a snook at the outdated past while laying the groundwork for the future trajectory of Jackie's career as the clown prince of kung fu. Unfortunately Lo Wei hated the film so much he refused to release it, seemingly rendering Jackie's hard work for naught. However two years later when the film was finally released, in the wake of Jackie's mega-star-making turns in Snake in the Eagle's Shadow and Drunken Master (1978), it became a substantial money-maker for Lo. Much to Jackie's chagrin although he took solace in having his creative instincts finally validated.
Opinion remains divided as to whether Half a Loaf of Kung Fu is a neglected gem in Jackie's early filmography, as many fans would have it, or as described by genre scholars Rick Baker and Toby Russell in their Essential Guide to Hong Kong Movies: a "turgid mess." Typical for many a late Seventies kung fu comedy the film's blunderbuss approach results in humour that is very broad and hit-and-miss, veering from laboured Benny Hill-style fast-motion slapstick and adolescent fart gags (most of which centre on a wacky 'crippled' kung fu master played by comedian-cum-innovative-studio mogul Dean Shek, best known in the west for his more dramatic turn in John Woo's bullet-strewn A Better Tomorrow II (1987)) to moments otherwise genuinely witty and inventive. Arguably its most memorable and ingenious sequence is the opening credits that merge wild acrobatics and camera trickery and see Jackie skillfully parody the likes of vintage Shaw Brothers wu xia ("swordplay") films, Zatoichi and old school chop-socky tropes; cannily poking fun at archaic conventions whilst showcasing his dazzling mastery of their forms.
Once the plot gradually veers away from its episodic, skit-laden first third the film finds its groove and becomes much more compelling. Essentially and atypically for Jackie it is a take-off on a King Hu scenario: ragtag band of heroes escort mystical Macguffin through hostile territory. As per Cantonese comic tradition the film establishes Jackie as a downtrodden yet wily braggard who lives by his wits: a chancer looking to make his name in a world seemingly indifferent to his ambitions, someone to whom Hong Kong filmgoers could relate. Jiang is a rough draft for the more sympathetic everymen that later became his stock in trade. Gradually Jackie's hapless nobody grows to exhibit real mettle, compassion and bravery before finally becoming a true hero. All of which the choreographer-star encapsulates by having the hitherto sluggish action grow increasingly fluid and dynamic, showcasing Jackie's true phenomenal skills. Despite too many superfluous characters, including a major villain that does not even show up till literally the last five minutes, the film benefits from Jackie being generous with the spotlight. Other characters including lovely Doris Lung Chun-Erh and Kim Jeong-Nan as the vengeful sister of the murdered martial arts master have their moments to shine. Especially in the last fifteen minutes that sees all the characters converge in a riotous brawl wherein Jackie wields Doris like a human weapon (!), twirls the bad guy's toupee like a nunchaku and struggles to decipher a kung fu manual with pages shuffled out of order. Indeed the finale aptly illustrates Jackie's improvisatory martial arts philosophy which is not that drastic a departure from that of Bruce Lee. But tell that to Lo Wei.