"I'm looking at treatments now for the sequel, but it's tough, 'cause there's so much crap out there."
---Hollywood (aka Prancer)
Any time a play makes topical references (i.e., to Arnold Schwarzenegger, CNN, black South Africa, etc.) it is inevitable that the meaning of some of those references may change over time as events unfold in the real world. (I'm sure the meaning of "flying head-first into the side of the World Trade Center" is quite different today than it was back in 1993.)
Since the playwright is not equipped to publish a new version of the text every Christmas to keep up with current events, the burden ultimately falls to the director to decide whether their production will be adversely effected by the latest developments and, if so, how best to deal with them.
Regarding Prancer Returns, my best suggestion is to simply ignore it. In my experience, late night theatre-goers rarely recall even the original Prancer until it is mentioned in the play, so the chances that more than a handful of them are aware of the sequel as well are pretty slim.
Still, if there is a serious concern that your audience will be familiar with the Prancer sequel - (for example, if Prancer Returns is airing in your area at the time of your run and your target audience includes a lot of adults with small children) - a simple fix would be to change Hollywood's line to: "I'm looking at treatments for another sequel."
Of course, this fix solves the problem for fans of Prancer Returns at the risk of creating further confusion for those who are unfamiliar with either movie. ("Another sequel? To what? When was the first sequel?")
Again, if it were up to me, I would simply not worry about the real-life sequel to Prancer. Audience members who spots the "error" will most likely surmise - correctly - that the play was written prior to the release of Prancer Returns, and probably be very pleased with themselves for knowing this bit of trivia.