When “Solo: A Star Wars Story” opens Memorial Day weekend, fans will get the answers to decades-old questions about the origins of Han Solo, Lando Calrissian and Chewbacca. But behind one of this summer’s most anticipated movies lies another, more uncomfortable question: Who, exactly, is responsible for the final product?

The candidates include:

• Phil Lord and Chris Miller, the 42-year-old comedy directors behind the “Jump Street” series and “The Lego Movie,” who shot “Solo” for six months.

• Director Ron Howard, 64, who replaced Messrs. Lord and Miller when they were fired last June, finishing production and reshooting many of their scenes.

• “Empire Strikes Back” and “Return of the Jedi” screenwriter Lawrence Kasdan, 69, who wrote “Solo” with his son Jonathan. His presence on set grew alongside his dissatisfaction with the liberties Messrs. Lord and Miller took with the script, according to people close to the movie.