I think they close the gate late at night because the park is supposed to be closed and your not supposed to overnight camp in it. Closes at "dusk" is kind of a strange concept. I got locked in one time in a different park around here when my son was really young. It really wasn't "dusk" yet in my mind. I had to call 911 to get let back out because I wasn't sure who else I could find the number to at the time. This was before smartphones.

Did you get a chance to try out disc golf?