My son isn't that old yet, but I have made a point to discuss parenting and rules with my ex husband regularly to make sure we are keeping up similar expectations and consequences. We work hard to keep things close to the same at both houses and we make a point to get along and also, let my son KNOW that we communicate about these things, so he knows he can't just slip something by us, since we talk.
That being said, not everything is ever going to be exactly the same at both homes. And I must agree with previous posters that you can't really interfere with what happens in the Dad's home other than, talk to your ex, calmly, about why it bothers you and try to reach a compromise for the future. REALLY try to listen and understand your ex's Point of View, even if you don't agree, and try to stay calm. Also, talk to your daughter about why this felt sneaky to you and reiterate what worried you about the safety.
I also, personally think a 14 should be able to go to a carnival/fair, but only with an adult in attendance. The adult can back off, not hover, but stay close if needed, supervise enough to make sure the teens aren't drinking or whatever. Maybe a trustworthy couple can go with the teens.
Punishing your child will just make her close up more. Maybe warn her that next time she sneaks something by when she's at her Dad's like that, without at least informing you or having her father call and discuss it with you when she knows its something you don't want her to do, then there will be a consequence, ie: grounded for a week, or whatever you choose. Make sure you are showing approval when she makes good choices or talks about things with you, also!
Of course, I don't have a teen yet, so maybe you tried all of this and it didn't help, LOL. I'm just going on my own history of being a child of divorce, and how I communicate with my ex, even though my son is younger. Good luck!