Harry's foot placement...
There was a time many moons ago when a sex scene was referred to indirectly in a movie or on TV one party had to have their foot on the floor while in bed since this was assumed to make sex impossible (apparently the censors never watched much porn.) Just before Harry and Sally were to engage themselves we see that Harry does indeed have his foot on the floor. Then again maybe he was just prepared for a quick run out the door. Perhaps they did this knowing the movie would eventually be seen on TV. Or was Billy Crystal placating a possibly jealous spouse. We'll never know.
As an apologist turned authority I don't defend my comments because I am always right.