I was watching the episode with commentary for Where Did I Come From? with Carl and Dick. Carl mentions that they are watching a silent version of the episode while they are being recorded. Carl Reiner was able to recite practically the whole script. He knew all the timing, the words, the nuances and would repeat them as they came up. Now, I know that we can recite whole scripts, but I thought that that was interesting that the producer loved the show that much that he could still recall the script years later. Carl was also able to recall how they edited and what they did.

P.S.Dick was not as quick to recall things, especially dialog. He was quickly able to recall the physical humor he had to do.

I noticed that too. I was surprised that they were watching with no sound, considering how much Carl could recall. However, and I think it was in this same commentary, Carl has admitted to watching the repeats when the show was on N@N.
Dick apparently doesn't watch the show anymore, hasn't in years, and, you're right, really doesn't remember many lines. For example, the Joy commercial. He doesn't remember doing it at all.

Steve

My 20-year-old nephew met Dick last night at the Chita Riviera review in NYC. He said he was so nice and kind. He talked with everyone, signed for everyone, took pictures, danced with a few people, totally down-to-earth. A real gem of a guy.