The play received 'mixed' reviews. = The play's reviews were 'mixed'. [=some critics liked the play, while other critics did not]
I accidentally 'mixed up' the two files. [=I put each of the files in the place where the other one should have gone]
He 'got mixed up in' a plan to destroy the government. [=he became involved in a plan to destroy the government]
(..) take care of the child. Oh, I never thought things would come to this... not in my factory. I'm sorry you boys got mixed up in this. Especially you,James. But now we can set everything straight again for the good of the company. ( whirring ) (..)2001 Monsters, Inc.