Chain Chomp Tattoo
This easter egg can be seen multiple times throughout the movie.
Chain Chomps are recurring enemies in the Mario video game series, first appearing in Super Mario Bros. 3. While normally they appear as a ball and chain, they can sometimes be seen without their chain, such as in Mario Kart 64 on the Rainbow Road map.
If you look closely (pausing may be required for a clear picture), you can see a Chain Chomp tattoo on the outside of Maui’s left arm right above the elbow. As explained above, this tattoo references the Chain Chomp variation seen without it’s chain.