Which canceled Lego Movie spin-off was announced in March 2015?

The canceled Lego Movie spin-off announced in March 2015 was The Billion Brick Race. Warner Bros. described it as another theatrical project in the expanding Lego film slate, separate from the main series and the already announced character spin-offs.

Jason Segel and Drew Pearce later joined as co-directors and co-writers in 2016. In 2017, Jorge R. Gutierrez replaced them as writer and director, and the film was scheduled for a May 24, 2019 release. Its concept developed into a Lego racing adventure inspired by movies such as The Cannonball Run.

Gutierrez eventually left the project in 2018 and later confirmed that it had been permanently canceled. Concept art released in December 2019 showed some of the planned characters, while later comments indicated that Diego Luna and Emma Stone had been envisioned as the voices of the two leads. The title is easy to confuse with Lego Superfriends, which was the planned Batman sequel.