AA doesn't work here, mostly because it's not needed.
You generally don't AA 1x2 lines, except when you want them very smooth. Only the moon might need some, and the red is just too eye-catching for that.
3-color pieces are meant to be pixely anyway.
Composition is rather boring atm.
The foreground is an alignment of items without real interaction, the focus of the piece (red guy) is way to the side, the general fg 'scape' parallels and avoid the skyline instead of playing along with it.
The red isn't used to the best of its composition powers. For instance, a red moon would balance the red guy, a third red element could complete an eye-driving triangle (not the pizza sign: it catches the eye because of red and type but it doesn't seem to have a real part in the story).
If you want that red to 'make things pop', you need to think it out carefully!
Other possible options: red city bg; red sky.
Nitpicks:
Why are some trees leafless while one has leaves? What is the pile of stuff below the Pizza sign?
The tree branches are not very nice; practice those from refs or life!
The little bits of lines at the angles of buildings are annoying.
Lamps are too big with boring detail; they'd be best lost in their own glare.
