Confusion with MLB and NBA logo?

When you ask this way, it begs a “NO” answer. You state the trademarks are similar. You state they are both for related sports. And, confusion is likely.

Can I trademark a version of the US Flag?

It depends. There are many registered trademarks that incorporate common aspects of flag. If you would like to see some of these registered marks, you can search.

How to use the ® and TM Symbol

how-to-use-tm-symbol

Can I legally use the TM symbol before I apply for a trademark registration? Yes. But not the ® (circle r) symbol. Learn to use trademark symbols properly.