A few mild exclamations such as 'oh my—' (cut off), and some crude/bathroom humor including a brief scene referencing plumbing and toilet humor. Donkey Kong makes a couple of mildly rude remarks. No profanity or slurs.
Frequent cartoon-style action violence consistent with the video game: characters are punched, knocked around, thrown, and hit with shells and fireballs. Bowser threatens characters and destroys a kingdom (the Penguin Kingdom is overtaken). Mario is repeatedly hurt during training sequences. Bowser imprisons Luigi and threatens him, which could be mildly frightening for very young viewers. A large climactic battle involves explosions and peril. All violence is slapstick and comedic with no blood or injury consequences.
The fantasy world includes magical power-ups (Super Stars, Fire Flowers, mushrooms that grant abilities). Bowser's character uses dark magic/fire-breathing. Kamek, a villain, uses a magical wand. These are all presented within a lighthearted video-game fantasy context, not as real-world occultism or spiritual practice.
Strong themes of brotherly love, loyalty, and family. Mario risks everything to rescue Luigi. The brothers support each other and refuse to give up. Courage, perseverance, and self-sacrifice are central to the story. The father-son relationship is shown with some tension but ultimately with love. Princess Peach is portrayed as a strong, courageous leader protecting her people.
While working underground to fix a water main, Brooklyn plumbers—and brothers—Mario and Luigi are transported down a mysterious pipe and wander into a magical new world. But when the brothers are separated, Mario embarks on an epic quest to find Luigi.