Dangling preposition - a preposition usually at the end of a clause that has been separated from its object.

E.g., Which therapist are you talking to? should be To which therapist are you talking?

Dangling participle - a participle usually at the beginning of a clause that doesn't have an obvious noun to modify

E.g., Talking to my therapist, the time passed quickly should be Talking to my therapist, I passed the time quickly (or better yet Time passed quickly as I talked to my therapist).