Sunday in the Park with Fran - S1-E18
Continuity mistake: When Fran is sitting at the table with Grace when C.C. is on the phone, the coloring book in front of Grace is open. Fran goes to pick it up, the shot changes, and Fran has already picked it up.
Sunday in the Park with Fran - S1-E18
Continuity mistake: When C.C. is trying to get Grace to play with the son of the Broadway critic she is coloring with a green crayon. Near the end of the scene it is suddenly a red one, and the paper she is coloring on is all red with no green so she could not have changed colors.
Answer: Mr. Sheffield needed someone to manage the kids, not necessarily babysit them. Brighton was a Bart Simpson type, Maggie was shy and awkward and Gracie had personality issues.