Correct your friends in private. Doing it in front of an audience is about you, not them.

Correcting somebody in front of other people stacks a second problem on top of the first. Now they are handling the mistake and being watched, so nearly all their attention goes to the audience rather than to what you said. Very little gets learned in that state. Everybody present also notes quietly that you are willing to do this, which changes how safe you feel to be around.

Take it to the side and say it once. Lead with what you want them to do differently rather than a description of the failure. Defending someone publicly and correcting them privately is one habit, not two.