The retail outlet's Cardiff branch is reportedly using promotional posters littered with mistakes, according to Nintendo Gamer.
The inaccurate poster features a 3DS XL with a second Circle Pad in place of the D-Pad and a larger telescopic stylus.
It is believed the image being used is a mock-up created by a disgruntled gamer after the 3DS XL was unveiled by Nintendo.
Announced last month, the 3DS XL gives players a total of 90% more screen space.
The battery lasts between three and a half to six and a half hours when playing 3DS games and between six to ten hours when playing original DS software.
Players will be able to transfer all account information, Play Coins, StreetPass Data, unlocked hats and Activity Logs to the new device, but will need their original 3DS to do so.
It will also come with a 4GB SD card, compared to the 2GB that ships with the original.
The 3DS XL will be available in Europe on July 28 and North America on August 19.
> Nintendo 3DS XL: Should you upgrade to the larger handheld?
Picture gallery - view 3DS XL images below: