Heavy QC incoming. Take it as constructive criticism for the future, and you'll certainly have a better QC period with your next project. The point of QC is ultimately to make the project look better, and to make you a better editor. In other words, we're only here to help.
The best example of your eraser mistake is on 2.png, at the very bottom, "happy" is surrounded by grey. Consider calibrating your monitor if you can't see it:
Sometimes it's easy to screw up the eraser tool (especially if you're early on in your Photoshop experience). Make sure your brush color is set to white, then try erasing. Consider using a dust layer to be able to see the difference between a white eraser and a gray eraser, like kamyu did earlier. You can use a dust layer like so:
(The technique is shown on the left page. Please ignore the bit about white leveling, it's not pertinent). Alternatively, consider using primarily selection tools to clean, like so:
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