Apparently someone at Microsoft forgot to run “find and replace” in the Surface Pro 3 user manual, which makes several references to the non-existent Surface Mini tablet.
The error was first spotted by Paul Thurrott, and it's still possible to download the guide from Microsoft's website. (The site sometimes spits back an error message, but we did get a PDF document to download after several attempts.)
The manual specifically mentions the “Surface Mini” on four occasions. It talks about pairing the Surface Pen to the Mini, using the pen in conjunction with the Mini, pushing the pen button to jump into OneNote and locking the Mini's screen orientation.
Microsoft has never confirmed the Mini's existence, though several unconfirmed reports claimed that it would appear alongside the Surface Pro 3 at a press event last month. Instead, Microsoft only announced the Pro 3, which just landed on store shelves today. Prior to the event, numerous rumors suggested that the the 8-inch Mini tablet would run Windows RT and include a stylus for note-taking.
According to both Bloomberg and Neowin, Microsoft management decided to pull the Mini at the last minute. It's possible that Microsoft didn't think the product would stand out enough in the brutally competitive small tablet market, or that the company is waiting on a proper touch-based version of Office. Panos Panay, the head of Microsoft's Surface business, did tell Bloomberg that the company is still working on a smaller version of the Surface.
While the manual doesn't tell us anything we didn't already suspect, it does add credence to the reports that Microsoft nixed the smaller tablet at the last minute. Either that, or Microsoft just wanted to get a kick out of watching the press react on a slow news day.