Yo es que leí esto sobre el tema de Brando:

the producers (Alexander and Ilya Salkind) announced that Marlon Brando's completed scenes for Superman II would be excised from the movie in order for them to avoid having to pay the actor the reported 11.75%[2] of gross U.S. box-office takings he was now demanding for his performance in the sequel. Donner publicly lambasted this decision, announcing that he would make the film his way or not at all. The April 1978 issue of the sci-fi magazine Starburst quotes Donner as saying, "That means no games...They have to want me to do it. It has to be on my terms and I don't mean financially. I mean control."

Tensions had existed between the Salkinds and Richard Donner throughout the almost nineteen months of filming it had taken to complete Superman and most of Superman II. The producers blamed the director for going wildly over budget and schedule. Donner claims he was never given a budget, nor a schedule. In the commentary track on the 2006 DVD release of the theatrical version of Superman II, co-producer Pierre Spengler recounts that Donner was indeed invited to return to complete the film as director, but, according to an Army Archerd/Variety magazine interview, Donner declared that if Spengler remained on the picture, Donner himself would not return to direct. In the same commentary, Ilya Salkind states the removal of Spengler was allegedly one of many demands made by Donner, who, he claimed, also wanted final cut of the film and more control over the production, demands to which the Salkinds were not willing to agree.

The situation finally came to a head, and on March 15, 1979, the Salkinds decided to replace Donner with U.K.-based director Richard Lester