Directed by Phil Lord and Chris Miller, and featuring the voice talents of Chris Pratt, Elizabeth Banks, Will Ferrell, Liam Neeson, Channing Tatum, Jonah Hill and Morgan Freeman, the animated film is set in a world built of the iconic plastic blocks and peopled by mini-figures representing ordinary folks like good-guy protagonist Emmett and tech-savvy Wyldstyle, as well as DC Comics superheroes such as Superman, the Green Lantern and the aforementioned Batman, and various villains.
Asked at a recent press conference at Legoland in California how he prepared to play the role, Arnett joked, "I read the Old Testament repeatedly.
"Phil and Chris and I talked about looking at all the Batmen who have come before -- back to the Batmen before the dinosaurs and Shakespearean Batmen. We were trying to see what would make us laugh and what we liked about all those Batmen. The first couple of sessions were spent finding out what was working and what wasn't. We kept hitting on [how] the more serious he took himself, the funnier he was and that's kind of where we ended up."
When it came to creating a back story for his character, Arnett said he had "the easiest job" of all the voice actors.
"Everybody knows who Batman is," he noted. "But what was fun was taking that kind of iconic character, a character that is such a part of the fabric of popular culture and kind of changing the rules to him a little bit. That was fun and that was funny to me. Because he is not necessarily the Batman that we've all become accustomed to."
"I thought he was cool, though," chimed in Freeman, who co-starred in director Christopher Nolan's recent Batman film trilogy, as well as lent his voice to a character in "The Lego Movie."
"Thank you!" Arnett said to Freeman, who was sitting beside him at the press conference. "I'm never going to forget you saying that. In the end, [my version of Batman] redeems himself and he realizes [his love interest] Wyldstyle should be with Emmett because he ultimately appreciates what Emmett does."
Another perk of starring in the kid-friendly flick is that his own sons are now thoroughly impressed by what he does for a living, Arnett revealed.
"I have a 3-year-old and a 5-year-old and they are extremely excited. My youngest -- I love it -- he keeps referring to it as the 'Lego Batman' movie," Arnett teased. Addressing his co-stars Freeman, Pratt and Banks, he added, "Sorry guys, they're really excited."
"The Lego Movie" is in theaters now. It earned rave reviews from critics and more than $87 million at the global box office when it opened last weekend.