Visible crew/equipment: When Quaid and Melina hop into Benny's cab and are being chased by Richter, watch Benny. During the shots where the perspective is from behind Benny, you can see that it is a stunt driver in the car. His head is shaved neatly, yet Benny's hair is curly and frilly all over. (01:11:00)
Visible crew/equipment: When Bob abruptly leaves his office due to Quaid's schizoid episode, a boom mic can be seen in a reflection on the glass, immediate left. (00:18:35)
Answer: It depends on whether you choose to believe the events of the film are real or in Quaid's lobotomized brain. If the events are real (i.e. Quaid is actually Houser with his memories blocked) then Harry is from the agency and is there to make sure Quaid doesn't say or do anything that would potentially break his memory block (like going to Recall). If you believe everything is in Quaid's mind after he goes to Recall, then Harry really was just his friend.