Picking out truthful quotes that say nice things in an otherwise overwhelmingly negative review is probably ok. For example, suppose the review says, "This is such a piece of junk that I don't know where to begin. First, the one positive thing: Susie Smith can sure dance." The theater quotes, "Susie Smith can sure dance."
In contrast, leaving out the ellipsis or a later chunk of the quote in certain circumstances may result in fraud, e.g., changing "You won't waste your money if you're smart" to "You won't waste your money," or, worse, "This is not worth seeing" to "This is worth seeing." Even a change to "This is ... worth seeing" may be fraudulent.
It's hard to imagine a regulatory body, such as the FTC, coming down on a theater for false advertising. If the organization receives grant money, however, especially from a government agency, the agency may be able to do something. Also, a critic whose words were mangled may POSSIBLY, under the right circumstances, be able to sue the theater under some form of libel theory. For example, if the theater misrepresents what a critic said, and the critic's reputation suffers because of it, a libel suit may be possible. Still, it's an unlikely scenario
Audrey, the Phantom Phanatic, who nonetheless would rather be Jean Valjean, who knew how to make lemonade out of lemons.