If you loved LEGO DC Comics Super Heroes: The Flash, try Justice League: Throne of Atlantis
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
You already loved

LEGO DC Comics Super Heroes: The Flash
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Justice League: Throne of Atlantis
What they share
Both films are directed by Ethan Spaulding, and they both carry the playful mood tag, and they sit in Adventure / Animation / Science Fiction territory. If that's the register that drew you to LEGO DC Comics Super Heroes: The Flash, the second film will land in a comparable space — through a different lens.
playful
What Justice League: Throne of Atlantis is
You live with unexplained powers in a world on the brink and then underwater kingdoms declare war on the surface, the Justice League forms an alliance with a young hero, Ethan Spaulding brings this aquatic battle to life.