3. Michael Riley is married not.

Mistake Correction:

The original sentence is 'Michael Riley is married not.'

1. Mistake: The adverb 'not' is placed incorrectly in the sentence.
2. Correction: The adverb 'not' should precede the verb or auxiliary verb it negates. In this case, it should follow the auxiliary verb 'is'.

Corrected sentence: Michael Riley is not married.