This was a private screening with no admission charge, and you had to reserve seats ahead of time; you also had to sign a promise that you wouldn’t record the movie while you were there, and they were checking ID. Everyone in my family reserved seats under our own names, myself included. There was no attempt to "sneak in" [emphasis mine]
Others may be crashing because they want to trash it before it even gets reviewed by the media. P.Z. Myers, who was not let into a showing last night in Minnesota, probably falls in the latter category.
No surprises. Myers (and Dawkins) did not "crash" the viewing – he applied for tickets just like everyone else (scroll down to the MN viewing at the Bloomington Mall of America AMC 14 showing; screen capture here just in case it slips down the memory hole).
Bruce Chapman is telling lies, plain and simple. I seem to remember a commandment against that.
Update: As this Panda’s Thumb post notes, “If Expelled expected these showings to be ‘private’, why would they provide a public RSVP site where anyone can signup to attend one of the many showings of the movie?” And the DI has issued a, *gasp*, press release. Imagine that.