Some of the things I've noticed:
Sights: the changing leaves, cats, leaves blowing around, people's Halloween yard decorations,
Sounds: wind chimes, the sounds of the wind rustling the trees, the sounds my shoes make on different parts of my walk, dogs barking, the sounds of leaves blowing across the road
Smells: smells of meals cooking and other not so pleasant smells (like the big pile of dog doo lol)
Touch: The warmth of the sun on my skin (not today obviously lol), the feeling of the wind on me, sometimes stiffness or soreness in my body
It's almost like a meditative walk doing it this way because I am really concentrating on what is around me and paying attention to it in a way that I don't do very often.
If you've ever done this (or if you do it now), tell me all about it! I really want to know what you think.
Oh, and another thing I've noticed? I walk A LOT faster when it's cold outside lol!