Although it may look quite comical, depending on how long these deer were stranded for they were probably very uncomfortable. The father decided the best way to attach the deer was to carefully and gently tie the rope around their legs, just below the knee.
One of the men stood at the back of the hover craft to keep an eye on how the deer were as they were slowly being pulled along. They wanted to ensure the rope stayed a little slack at all times, so that it never pulled on the deer. It seemed the deer were quite content with being pulled along to safety.