Just FYI, the menu photos on Yelp are not guaranteed to be up to date, either. The only real way to see what the restaurant's actual menu is without going there is if they have it up on their own website.
It's more common than you think though. I know of restaurants that change their menus daily or weekly. Most don't, but you will run into it if you eat at enough places, and I highly doubt someone is going to post a new photo of the menu every week.
Or just ask the human being on the phone with you if $ITEM is still being offered for $PRICE. The beauty of communicating with humans instead of machines is there are no rules, you're allowed to go 'off script' like that.
