Four wheel brakes appear to be present in this Peerless. 1923 was apparently the year that four wheel brakes started to became standard for the industry. Having rear wheel braking only makes for extremely unstable stopping.
http://www.carhistory4u.com/the-last-100-years/parts-of-the-car/brakes

It's a gas can. It even says "GASOLINE," stenciled on the side! The running-board mounted frame secures it all around and over the top. Also common in those days was a trio arrangement of smaller cans in a similar carrier for gas, oil, and water.

Peerless was an upscale make, but those hood latches are a type that shakes loose pretty easy, thus the rope through all four latches, to keep them fastened.

I believe but cannot say for certain that those fitted windows were factory accessories. Again, not an economy car.

At first I thought Mr. Backseat was lighting a cigarette, but now I'm leaning toward the snack.

1) Tools, perhaps?
2) That strap is crossed over on top, and looks like it's holding the hood latches up. I could see how they might loosen on rough roads, and this car looks like it's seen some!

But I think that might be a tool case on the running board. I'm wondering if the occupants have some kind of card game going on.

[Looks to me like they're having a snack. -tterrace] Looking again dang it. I think you're right tterrace. My 500th comment since joining Shorpy was not my best.

What is on the driver's side running board? And what is the rope or cord on the hood holding up on the passenger side? Are the windows aftermarket?