Old thread, but I've thought about both sides of this phenomenon a fair bit.
I have vague memories of seeing sand cat, short-beaked echidna, and I believe fennec fox in Riverbanks Zoo's Conservation Outpost as a kid in the early-mid 90s (not necessarily all on the same visit). It's a small mammal area so both of these species make sense to have been there, but I can't find anything that corroborates their presence there at the time. It's not a big deal either way, I've seen all of these species in earnest since, but I wish I could establish whether these are real memories or fabricated.
Similarly, I distinctly recall a small, round exhibit open exhibit containing young alligators or perhaps caimans at Greenville Zoo, just outside their reptile house from the same time period. I can see it so plainly, but the exhibit I'm picturing makes no actual sense as something a zoo would have actually had. It seems like a major safety liability, given how close and accessible they would've been to guests, even if it was just small crocodilians.
On the flip side, there's quite a few species that would be life listers that I almost certainly (or at least plausibly) have seen, but have no concrete memories of. These include spectacled bear (at both Riverbanks and Lincoln Park), arctic fox (Riverbanks), Pallas's cat (Lincoln Park), aoudad (Waccatee), and most disappointingly, Dall sheep (Waccatee). I feel pretty confident about picking the rest back up and adding them to my list at some point in the future, but not fully appreciating the Dalls at the time feels like a huge miss (well, as much as I could've appreciated them, given how deplorable that place was).
