The film is essentially a feature-length NickToons cartoon, with all the wackiness and surrealism typical of the genre. It is the third live action/animated movie the characters were featured in, the first being Who Framed SpongeBob SquarePants and the second being Sponge Jam. Despite being a box-office bomb, the film was a moderate critical success. It was also the last film to feature a score by veteran composer Jerry Goldsmith before his death in 2004.
Tired of playing second fiddle to SpongeBob, Patrick demands his own movie from Nickelodeon only to be fired by VP of Comedy Kate Houghton. DJ Drake, son of action star Damian Drake, is also fired from his job as a security guard when trying to escort Patrick from the studios, driving the Batmobile into the studio's watertower which falls on Kate's car. Kate tries to make SpongeBobs' film more educational and socially relevant, but he refuses to work with her unless Patrick is brought back; she is ultimately forced to comply to keep her job after Bugs is injured during a routine that required Patrick's presence. DJ returns home and is surprised to find Patrick snuck along. Finding a hidden video screen, DJ is told by his actual super spy father to go to Las Vegas to find a woman named Dusty Tails to get a diamond called the Blue Monkey. DJ and Patrick head out in an old AMC Gremlin car. SpongeBob and Kate arrive at the house after SpongeBob callsPatrick and learns the situation, and pursue them in Damian's spy car, a TVR Tuscan right hand drive. Also after the diamond are the Acme Corporation run by Mr. Chairman who plans to use the diamond to take over the world and sell more Acme merchandise.
DJ and Patrick arrive in Las Vegas and find Dusty Tails performing at a casino run by Yosemite Sam. Dusty gives DJ a playing card with the Mona Lisa's face on it. Yosemite Sam, working for Acme, pursues DJ and Patrick across the city, leading to a car chase with SpongeBob and Kate being dragged into the mayhem when DJ takes the wheel of the spy car. The heroes escape via the spy car's flight ability whilst Yosemite Sam crashes into his own casino. The spy car crashes in Death Valley where the heroes conviently find a Wal-Mart thanks to Kate's desire for more product placement. Mr. Chairman sends in Wile E. Coyote to kill the heroes but he fails via a misdirected missile. The heroes wander into Area 52, Area 51 created as a "paranoid fantasy" to hide Area 52's identity, where they meet Mother, a Q-like figure who gives DJ new gadgets to help find the diamond and reveals that Acme will use the diamond to turn mankind into monkeys to create their merchandise and then turn them back so they'll buy the products. Marvin the Martian and a group of famous aliens (including two Daleks) attack, but the heroes escape. They conclude the next clue is in the Mona Lisa painting in Paris.
In the Louvre, the heroes discover the playing card doubles as a viewing window and find a map of Africa behind the Mona Lisa painting and take a photo on Kate's mobile phone. Elmer Fudd arrives to gain the card, turning out to be "secretly evil".SpongeBob and Patrick flee playfully around the museum, leaping through various famous paintings until Elmer is defeated by SpongeBob via a fan when he jumps out of a Pointillism painting. Mr. Smith, henchman of Mr. Chairman, steals Kate's phone. The heroes travel to Africa where they hitch a ride on an elephant ridden by Sylvester the Cat, Tweety Bird and Granny. They find the diamond and a temple, but Granny and the others reveal themselves to be Mr. Chairman, Mr. Smith and the Tasmanian Devil. Mr. Chairman uses a disintegration pistol to transport himself and the heroes to Acme Headquarters and gains the diamond. Mr Smith is revealed to be the Tasmanian she-devil.
The diamond is taken to a satellite by Marvin; Mr. Chairman explaining he will fire an energy beam worldwide which will turn everyone into monkeys aside from himself and his love interest, Mary. DJ and Kate save Damian from being killed and Wile E. Coyote blows up in a train. SpongeBob and Patrick chase Marvin to the satellite, and while SpongeBob fights Marvin, Patrick becomes Star Dodgers and manages to destroy the satellite by plugging its dish with his beak. SpongeBob defeats Marvin by overloading his own bubble gun. The energy beam strikes Mr. Chairman, turning him into a monkey. Later, Patrick learns the entire adventure was part of SpongeBobs' film, but SpongeBob suggests the two become equal; Patrick starts cheering until he is flattened by the NickToons title iris ironically. While Porky Pig tries to say his ending line,"Th-th-th-that's all folks," the studio starts to close. After that, when it's almost pitch black, Porky tells the audience to go home. In the credits we see drawn characters from the movie.
In the post credits scene, Patrick goes back to the casino and pulls a trick on Nasty Canasta and Cottontail Smith (The two that pair with Yosemite Sam in his casino scenes).
Despite its financial failure, the critical response for Back in Action was mixed to positive, making it more critically successful than the previous NickToons film Sponge Jam. As of March 28, 2011, the film scores a 56% "Rotten" rating at Rotten Tomatoes; however, at Metacritic, the film ranks 64, with "generally favorable reviews". The two well-known movie critics Roger Ebert and Richard Roeper both gave the film two thumbs up. Along with the critical success, the film was also nominated for Saturn Award for Best Animated Film, Annie Award for Best Animated Feature and Satellite Award for Best Animated or Mixed Media Feature
The original title for the movie was going to be "Spy Jam" and Jackie Chan was to be the lead actor.
Budgeted at $80 million, but grossing only around US$21 million (US$68 million worldwide), Back in Action was a financial flop. There were multiple causes to the film's demise theatrically. On the front of family films, Back in Action was sandwiched between the releases of Elf and The Cat in the Hat, resulting in Back in Action being lost in the shuffle. It should also be noted that this film was released the same month as another Warner Brothers film The Matrix Revolutions, which the studio put more advertising money behind. Only the barest minimum of promotions were done to advertise the film, limited to advertising with the film's promotional partners (Sprint, McDonald's, Aflac, among others) and very few television ads. Also, very little merchandise directly based on the film was released beyond some toys made by M and M's, a junior novelization, and a Hallmark Keepsake Ornament. The film's poor box-office results discouraged Nick. from releasing the newer NickToons and Ren and Stimpy shorts that Nickelodeon had completed, and they cancelled those in production.