Sly, Bentley and Murray attempt to recruit Murray's Guru in Australia.
Tropes:
- Arc Villain: The Mask of Dark Earth.
- Artistic License – Geography: Australian geography is inaccurate, as both Uluru (referred to as Ayers Rock in-game) and Wave Rock are in Yuendumu, Northern Territory. In reality, Uluru is by the South Australian border, over 600km away from Yuendumu, while Wave Rock is near Hyden, Western Australia, which is nearly 300km away from Perth.
- Artistic License – Nuclear Physics: Part of "Operation: Moon Crash" requires slathering Murray in radioactive petroleum oils to make him glow in the dark. One of the jokes is Bentley instructing Sly and Murray to carefully collect the oil (implying that radiation is still deadly in-universe), only to show Murray dancing in the oil. If the radiation in that stuff is so potent that it's glowing, it should have killed both Sly and Murray the moment it reached the surface without protective suits on. If not, the cancers and other health defects it would cause would have rendered the both of them unfit for the Cooper Vault job and would likely have killed them before the fourth game.
- Colossus Climb: In order to get the Mask of Dark Earth off of Carmelita in "Operation: Moon Crash", Sly climbs her clothing. He starts from her boot laces, scales the seams of her pants, and sneaks up her jacket and into her hair to reach the Mask's latching points.
- Evil Mask: The Mask of Dark Earth serves as the main antagonist. When the mask possesses someone, they grow bigger and become more aggressive. After its host dies, it will escape by floating away.
- Failed a Spot Check: The miners never seem to notice the Mask of Dark Earth floating around and possessing their comrades all across their settlement until Carmelita grows to kaiju levels.
- Giant Woman: Carmelita becomes this during "Operation: Moon Crash". She initially becomes about double Sly's height when she interrupts the Cooper Gang's plan to destroy the Mask of Dark Earth, resulting in it getting onto her face. Bentley tries to sedate her with his tranquilizer darts, but they only make her bigger, large enough to carry one of the miners' big trucks sandwiched between her arm and her body. The Cooper Gang subsequently attempts to use their own big truck to escape from Carmelita and take her down with the Exploding Barrels she throws at them, but these attempts only make her even larger. By the final part of the mission, she's easily carrying the stolen truck in one hand, and the Coopers' truck doesn't even pass her boots. In order to remove the mask, Sly has to climb up Carmelita's clothes to reach the mask's latching points, causing Carmelita to swipe at him and break the pieces herself.
- Heavy Voice: When Carmelita is under the effects of the Mask of Dark Earth, her voice gets deeper as she gets larger.
- Impossibly Graceful Giant: After first being possessed by the Mask of Dark Earth, Carmelita is still able to do her areal somersaults despite her now giant size. It's unknown if she could still do them after her size was further increased by Bentley's darts, but she does get a lot faster. She is shown moving very slowly after her final increase from the dynamite, though it's stated she's not moving at full speed and that at her full speed, the gang can no longer outrun her in their giant truck.
- Land Down Under: The Guru is an aboriginal koala with Dreamtime magic, the miners are all kangaroos and dingos mining for opals, there are crocodiles, visits to scenic Ayers Rock and Wave Rock and most of the music is done in didgeridoos.
- Living MacGuffin: The Guru. Help him drive off the miners and destroy the Mask of Dark Earth and he will join the gang as their Token Wizard.
- Make My Monster Grow: The Mask of Dark Earth does this to anyone it possesses. It even possesses Carmelita, resulting in a boss battle against her.
- Mini-Boss: With the exception of Carmelita, every mook the Mask has possessed counts as this.
- Operation: [Blank]: "Operation: Moon Crash" starts with the Guru using his powers to dispose of the gyro-copter. Murray will pose as the Mask's enemy the Moon Spirit to attract the Mask, who Murray with then Thunder Flop into oblivion. With the Mask and its corrupting influence gone, the already on-edge miners will leave, Murray will be free to rejoin the gang, the Guru's life-long task will have ended and he will join the Cooper Gang.
- Sealed Evil in a Can: The Mask of Dark Earth was long-imprisoned in the area before the opal-miners unwittingly unleash it, the Guru having been tasked with making sure such a thing never happens.
- Shown Their Work: In spite of the inaccurate locations of Uluru and Wave Rock mentioned in Artistic License, the map of Australia shown in the opening cutscene is accurate, with the states names and boundaries, capitals, major towns and cities, and highways displayed.
- Toxic, Inc.: The mining operation is doing a lot of damage to the environment, producing massive amounts of toxic sludge and creating general instability in the various areas of the level.
