But Warner stumbled with “The Lego Ninjago Movie,” which arrived in third place with $21.2 million in ticket sales — sharply less than box office analysts had predicted going into the weekend.

“It was a much younger audience than we were hoping for,” Mr. Goldstein said, noting that 46 percent of the “Ninjago” audience was under 18. The movie played in 4,047 domestic theaters and cost roughly $70 million to make, not including marketing.

The animated “Ninjago,” based on a ninja-themed line of toys, is part of a Lego-based “cinematic universe” that Warner has called a business pillar, with additional original installments and sequels exploring different genres planned for the next decade. But the future of the Lego movie franchise is now a serious question.

The first Lego movie arrived to a whopping $69 million in ticket sales in 2014. A Batman-themed follow-up had $53 million earlier this year. And now comes “Ninjago” with $21.2 million. The free-fall does not bode well for “The Lego Movie 2,” which is scheduled for release in 2019.

Many people in Hollywood say the reason for declining returns is obvious: Warner, in search of franchises, released too many Lego movies too quickly. “Ninjago” may also have suffered from lackluster reviews, niche subject matter and a feeling among consumers that the property best lives on television; Cartoon Network has found success with the animated series “Lego Ninjago: Masters of Spinjitzu.”

Also of note over the weekend:

“Battle of the Sexes” (Fox Searchlight), set in the 1970s and starring Emma Stone and Steve Carell as tennis rivals, arrived in 21 theaters in seven cities and took in about $525,000, a solid result.