The misspelled words on the huge granite block were "sabbath," which came out "sabbeth," and "maidservant," which ended up "maidseruent," The Austin (Texas) American-Statesman reported Saturday.
Oklahoma state Rep. Mike Ritze, who sponsored the original bill to put up the monument, said Oklahoma is playing catchup with Texas, which already has a Ten Commandments marker in Austin.
"We in Oklahoma are very competitive with you all," Ritze said. "We wanted to keep up with our neighbor Texans."
Ritze's family donated $10,000 for the monument, while private donations covered another $10,000 to install it.
Activists say the money spent on the monument could have gone to fund other projects.
"We think it's unfortunate that legislators would spend time, money and energy to put a monument up at the seat of government that divides Oklahomans along deeply held personal beliefs," said Ryan Kiesel, executive director of the ACLU of Oklahoma.