Air in my plastic

I just started to make my own plastics. My paddle tails look good but my baby brush hogs have air in them. What am I doing wrong?

Injection or hand pours? You might have to inject and then hold pressure for several seconds and then top off the mold once or twice. Some of my molds need that when they are cool.

Thank you, I will try that. I am using an injection mold and 6oz injector.