The character outlines look odd, can I ask what program you're using to do it with?
If it's photoshop you can get a good effect cutting out the outlines fast by using the magic wand tool on the background and adding a 1-2 pixel feather to the selection. Else a glow can be very easy to add to cover it up. Other free software such as GIMP can also do this more than well enough.
Or there's plenty of other ways should you actually have more than 30seconds to do it in.