Oh, I do love edge cases!  Personally I would not recommend annotating the reflections in most situations, but it's a close call.  It almost definitely doesn't matter unless you have lots of images like this relative to your total data set, but in your case, you might, so I could be convinced.  Maybe I'm 51% in favor of annotating them in your case?

One of my all-time favorite camera trap images is the thumbnail we used on LILA for the NACTI dataset, I like it so much that I also use it as the fun image at the bottom of the main MegaDetector README:

This one is interesting, because IIRC both MDv5a and MDv5b identify the reflection when I run the reduced-size image (640px) that's used as a thumbnail, but not when they can see the full resolution of the original image (which MD would see at 1280px)... here's MDv5b run on the 640px version:

Other edge cases like this that have presented interesting issues in various datasets:

• Based on my very non-scientific anecdotal experience with suburban camera traps in England, English people seem to enjoy placing animal-shaped statues in their yards.  English WILDLABS folks, is that a thing?  In any case, they sure do look like animals if you're an object detector, in fact they often look like animals to my human eyes in a single image also.
• Lots of businesses in urban environments like to have giant animal painted on the sides of their trucks.  Sometimes those trucks are related to the animals (like a dog grooming business), but usually it's more like "we're the big elephant of local roofing companies", with a gratuitous elephant on the side of the truck.
• Carcasses set out as bait are a constant challenge... we usually don't annotate them as animals, but they are animals, just... messy ones.