No. That if they are done working - that's when your obligation ends. As to overtime, that would depend upon if they working beyond a normal 8 hour shift.
An employee is entitled to at least minimum wage and overtime pay at time and a half for all hours worked over 40 hours per week. However, the federal Fair Labor Standards Act (FLSA) and Pennsylvania’s Minimum Wage Act do not require overtime pay for “any employee engaged in a bona-fide executive, administrative, or professional capacity” who is paid on a salaried basis instead of an hourly wage. (29 U.S.C. § 213a(1), 43 P.S. § 333.105a(5)). When is travel time compensable?
To start with, commute time is rarely paid for. "Rarely," because there are situations in which a nonexempt employee will travel from his home to a job site and, if the travel time is greater than "normal" commute time, then most companies in most states will have to pay for the extra time.
However, when a nonexempt employee reports into a central office and then goes to a job site, the travel time to get to the site is considered as time worked and is compensable (and also counts toward overtime hours). The simple rule of thumb is that the employee's day starts when s/he reports into the office.
Most employers seem confused about travel time spent getting to out-of-town travel to seminars or workshops or trade shows. The fact that nonexempt employees must be paid for such travel time as time worked is probably one more reason why so few nonexempt employees are sent to anything but local workshops. The last problem is, just what is "travel time" when one goes out of town? Is it from the time the employee leaves his house to the time that he checks into a hotel, or is it from the time the employee leaves his house until the plane lands? What if he lands, has dinner, rents a car, and then gets to the hotel three hours after touchdown?