The woman, who has given her name to the news media as Christina Esquivel, said she felt someone pawing her during a lights-out period on the ride, the Los Angeles Times reported.
Esquivel said she used her own camera to grab a screen shot of a photo taken by Disney and intended to be sold to tourists as souvenirs. The picture shows a man in a baseball cap to Esquivel's left with his arm reaching in her direction.
The photo was taken just after the lights came back on.
It's not right," Esquivel told KTLA-TV. "I didn't do anything to deserve it, and he needs to pay for it."
Sgt. Rick Martinez of the Anaheim police said investigators got a copy of the picture from Disney and are also trying to identify the man.
Esquivel was at the park Friday with her daughter.