I think an otherwise fairly good sign but with the wrong scientific name is quite unusual. I wonder if someone put it there deliberately because they knew only a zoo nerd would notice.
I enjoyed this one, from a French zoo, for a striped hyena: well, the picture at least looks a little hyena-ish, and the animal has stripes.... Striped hyaena sign, July 2016 | ZooChat
It's funny when zoos make mistakes on signages, like the ones you all described.
Saimiri Sciureus (squirrel monkey, not bat eared fox), The green anaconda exhibit sign (anacondas can't attack a pygmy hippo, they live on completely different continents), The striped hyena signage (it is an aardwolf on the sign, not a striped hyena), and the misspelled sumatran orangutan (they put in the space one letter too late.)