You are right, Casual mode is endless and you get one point for each pumpkin. But, what happened with the reviewer? he instantly forgot the rules of the mode he has selected. This is really to be expected. While, you, as the developer, perfectly know that the mode is endless and there is a (slow) score, the player does not get the rules.
Here some suggestions:
1: as you said, exchange Challenge and Casual in the menu order; I would say that Challenge is the more “natural” mode for this kind of games
2: show the mode name in the play screen
3: change the score system for Casual: either
(a) no score at all, the player enjoys combining veggies as long as she/he likes (and no score indicator on screen, nor high score)
or
(b) score as in Challenge. As I said in my previous posts a very slow score is not very entertaining (my idea of course).
I hope this can help somehow.
Ciao!