From Marlon Biography by Peter Manso :
About Rita Moreno:
The Night of the Following Day, a low-budget thriller, had been announced in mid-September 1967 and quickly put into production four weeks later. Revolving around the kidnapping of a young heiress (played by British actress Pamela Franklin), the film features Richard Boone as a sadistic gang member, Rita Moreno as a drugged-out accomplice, and Brando, in a blond wig and black T-shirt, in the role of a kidnapper who undergoes a last-minute moral conversion and rescues the gang's victim.
......Rita Moreno inevitably brought her complicated history with Brando to the set. In his own strange way Brando had never been one to let go of his past conquests, and it was he who had insisted that Moreno be hired because she was "down on her luck."
Two years earlier, at age thirty-three, Moreno had married Dr. Leonard Gordon, a cardiologist from New York; she brought him and their baby with her. But as everyone in the company realized, she was still carrying the torch.
Marion Rosenberg, who saw the couple throughout the shoot, said, "The strain for Rita was all the greater because he was shipping in his various dusky maidens. I don't think Marlon meant to torture her, but just seeing him with all these other women . . . well, it must have opened up a lot of heartache."
"With Moreno back on the scene, things got crazy," said Rhodes. "She may have been there with Lenny and her kid, but Marlon was fucking her again. With Marlon, it isn't over until it's over."
The tension between Moreno and Brando erupted during a scene they were doing together in the third week of the shoot. The locale was a small villa in the dunes where Moreno's character was supposed to have been snorting cocaine or taking heroin, and Brando's character was to become angry at her and begin to quarrel.
"With the cameras rolling, Marlon broke off the top of a bottle and handed it to her to hit him with," recalled Rosenberg. "Suddenly their scripted fight became a real fight. Things were flying around, and she started to grab at his hair. They were hurling accusations at each other, and all her pent-up anger and frustration just came pouring out—and this with Lenny and the. child on the sidelines watching.
The room where we were shooting was so tiny that the cameraman was sort of plastered against the wall trying to get some depth to the picture. Some of it remained in the film, because even though she lost the script, she stayed in character."