Is it a myth that modern whales have been found with hind legs sticking out of their sides and full formed tibias, fibias, and toe bones? I keep finding assertions, but no citations. For example, the wikipedia page has no citation for it.
The link you give doesn't mention limbs sticking out of the body wall, but only vestigial hind limb elements. Many whales do retain pelves and femora, as this page at the Bergen Museum shows. Given the variation in limb development across vertebrates, it would not be surprising to find more distal elements (but I would be very surprised if they extended past the body wall).