The D.A.'s office has received numerous cases from the LAPD and the Beverly Hills police since the #MeToo movement launched last fall, but has yet to file a criminal charge.
The DA's office confirmed on Thursday that it was reviewing the three cases.
Entertainment news website "The Blast" said a woman had filed a report with Los Angeles police accusing Anderson of assaulting her past year after she catered an event thrown by the actor.
The case involving Weinstein brings the number under review by Los Angeles prosecutors to six.
According to TMZ, Weinstein and Seagal are among the three cases given to the L.A. County District Attorney on Thursday by Los Angeles Police Department investigators who conducted the probes.
The LAPD also submitted a sexual assault case on Wednesday against Steven Seagal. Actress Regina Simons alleges she was raped at a wrap party for the film On Deadly Ground in 1993 when she was just 18 years old. The D.A.'s office had earlier received an allegation against Seagal from the Beverly Hills Police Department. She claims she had been invited over to audition for a part in a Genghis Khan movie he was working on. The charge of committing a forcible sexual act in the first degree pertains to the allegations of a third woman, following the previous case based on the accounts of two other women.
Anderson, the lead in hit ABC sitcom "Black-ish" has been accused of sexually assaulting a woman more than a year ago.
Anderson's representative said in July that the actor "unequivocally disputes the claim".