UPDATED: Black Ops II discs inexplicably contain Mass Effect 2 data

Select players who purchased retail PC copies of Call of Duty: Black Ops 2 are discovering an odd, frustrating surprise.

Reports from the Call of Duty forums, Steam, and Reddit (among other sites) are claiming the second installation disc for Activision’s shooter is actually for Mass Effect 2.

Along with not making a whole lot of sense, the issue is preventing players from installing the game via retail discs – though each copy comes with a Steam key that allows the game to be downloaded in its entirety via digital means.

Activision has yet to provide any official comment on the mistake, but with a product from a completely different publisher involved it seems likely the situation would stem from a manufacturer error.

UPDATE: Bioware has jumped all over the news, posting a blog post entitled "We’re Answering the Call" that offers a free PC copy of the Mass Effect Trilogy to the first fifty people who contact the developer proving they’ve run into the printing error.

"Rumor has it that about a thousand customers who purchased Call of Duty: Black Ops II for PC today were also treated to a surprise copy of Mass Effect 2," the post states. "If you were one of the affected, chances are you thought it was a mistake, but we prefer to think that it was an omen, and when the universe talks, you should listen."