David Lowery was released from Strangeways prison, Manchester, shortly after a judge had ordered that he be held in custody. But prison staff told him he was free to go.
Lowery, 44, of Plumtree Court, Salford, Manchester, was arrested a month ago after allegedly raping a girl aged 13. He was charged with rape, abduction and false imprisonment.
After the judge at Manchester Crown Court had overturned an earlier decision by Salford magistrates to grant bail, Lowery was returned to Strangeways. However, a tick had been put in the wrong box on a form, indicating that bail had been granted.
Police were yesterday trying to trace Lowery, who had been missing for four days.