Basically the title. They’re going to encounter animals they’ve never seen before, or notice a complete lack of familiar animals. They’re going to notice the none of the plants are the same, and that there aren’t any domesticated plants other than what they may be carrying. They might try to go back the way they came and find it impossible.
Paul Sorvino’s misguided plan was well intended, but doomed to fail.
And then there’s the poor schmuck who wandered in from the holodeck.
Couldn’t grasp such radical notions. The rest of the tribe would likely react about the same.