I was in a hurry to leave for the office yesterday and forgot that my handbrake was engaged while starting. I started the engine, clutched, and reverse geared, and found the vehicle not moving backwards. I quickly depressed the clutch and retried. After these two attempts, I realized my error of not disengaging the handbrake.
I didn't step on the gas in the process of trying to move. I want to know if I have done any damage to my car.
No significant damage has been done. There are two potential areas that can be damaged by extended driving with the park brake on. The park brake shoes/pads will wear prematurely if the vehicle is driven with the brake engaged. The clutch will also suffer some wear as the brake being on will require slipping/riding the clutch on every start. In your case you caused no more wear than would occur by starting on a hill.
I want to know if I have done any damage to my car.
No, you're fine.
In this question, a user asked if driving 1000 meters with the handbrake on had caused permanent damage:
I drove with the handbrake on for 1000 metres
Our assessment then was that that driver had probably caused plenty of wear to the handbrake but not damage. Since you barely moved, you're almost certainly perfectly fine (if a bit embarrassed).
You are 100% fine. I don't think the people replying read that you didn't even step on the gas at all when trying to move. You didn't list what car you were driving but I seriously doubt your car would be able to generate that much toque to even cause any wear to your handbrake just by riding the clutch friction point.
