What part of “all promotional materials mentioning the California Science Center produced for your event (including invitations, programs, press releases, etc.)” is not clear?
The part where the "all", by legal precedent, is understood to apply narrowly to the signatory parties --- not to those not party to such agreements.
Think about it for a while. Try putting it in a different context, and think on how that may apply as a neutral principle of law.
Are you responsible for what some other person does? Can you, yourself be made to be contractually responsible for the acts of others---which you may have no control of? How would THAT work??? Would it be right & proper?