Breakthrough Hit: For Ubisoft Milan, which until then had primarily worked on low-profile handheld and "casual" games aswell as support roles on Ubisoft's bigger titles. The success of Mario + Rabbids caused the number of job applications to increase by 10 times as much and launched plans to expand the studio.
Cut Song: The Phantom was actually supposed to have 3 acts to his song, each of which would play during phase transitions, but the second one was cut out of the game. It can be listened to here.
No Dub for You: In regards to the scientist in the intro and the Phantom, this is the first Raving Rabbids production with full voiced dialogue to NOT be dubbed in the Rabbids' native French (for those not keeping track, the previous Rabbids productions with full voiced dialogue prior to this game were Rabbids Go Home and Rabbids Invasion).
Saved from Development Hell: A crossover between Mario and the Rabbids had been on the table at Ubisoft since the Wii era, but nothing came out of it until now. All that really came out of it was that it was supposed to be a subversive, self-aware take on Super Mario Bros. The only known piece of concept art dates back to 2010, depicting the Rabbids stealing Bowser and Mario chasing after them.
So My Kids Can Watch: A variant. Because the game takes heavy inspiration from X-COM, the director of the franchise has said that despite not working on the game, he's looking forward to it as an "XCOM game" he can finally share with his daughters.