I've had this movie for awhile and the UPC from the ad matches the one I have. The lower left corner of the back cover of my copy and both disks show both US and Canadian ratings. I got mine used, so it didn't have any inserts either. Mine also says "2008 DVD release", so it may have been marketed before the beginning of DMA codes.
Fakes are regionless as well, usually, but eBay would auto fill any domestic info. You'd likely know it was a fake with a low quality video or audio, the case would be made of cheap material (the clear plastic the disc slip goes inside would feel very thin and cheap compared to a "real" one), the print on the art would seem off or washed out due to it being a photocopy of the original print. Were there ZERO inserts? Disney didn't do DMA back then but that didn't keep them from stuffing the cases, though inserts being present isn't a pass necessarily. Check to see if the dates of any inserts match the release of the disc set.
Essentially if it's fake but you can't tell the difference, just roll with it. But most Hong Kong ripoffs mock the US releases and not the Canadian ones so you're proooobably fine