S1E7 Dragonshy Lyra is in the background while Fluttershy is running through the park trying to tell people about the smoke. I didn't notice the first time I watched the episode either. There might be other instances I don't know about too, so try to look for those as well.
I hope that that is simply a park footpath... Cause otherwise, that bench is actually in the street! This image is undeniably beautiful, and I would LOVE to trot up to Lyra and ask her if the seat beside her was taken!