There's a videogame convention in California. It's open to press, but not to public. If one was to get in somehow, and get caught inside, could that person get arrested or would he be simply asked to leave. Person would not disrupt anything, or do anything negative at all. Just look around.
Juvenile Law Attorney
Criminal trespass law is generally defined as an unwanted intrusion onto someone else’s property. In California, criminal trespass law is contained in the subdivisions of California Penal Code Section 602. There is a wide range of conduct that can result in a criminal trespassing charge, it is important to speak with an attorney about the specifics of your case to determine whether criminal trespass charges are imminent. If charged and convicted of misdemeanor California Penal Code section 602, you may receive up to 180 days in county jail, $1000 fine, probation, community service, CalTrans, stay-away orders, and/or restitution.
Disclaimer: This answer is provided as a public service and as a general response to a general question, it is not meant, and should not be relied upon as specific legal advice, nor does it create an attorney-client relationship.