They are right, I can't name all 100. I can maybe get a handful if I spend all day and night looking at the thing going crazy I got 2 or 3 off the bat because they were a bit obvious. Some of them I'm not sure how much of the image is the clue.
Normally I like things like that but the number of items to hunt for needs to be about a dozen or two and no more than 50 for me.