changing event dates in iPhoto

Don't they just reflect the dates of the photos inside the event? I think that is the case. Try changing the dates of the photos. If there are a bunch, the batch change will make quick work of it.

 

I don't see any option to change the dates of photos, whether in a batch or individually. Am I missing it?

 

If looking at a photo, look on the pane to the left. Near the bottom you should see some information, including the name of the photo and the date. Change the date there. For multiple photos, select the photos, then click on Photo>Batch change. You can change many things from there, including the date.