I've just got back from spending the day at the Auckland Comic-Con (although it's actually called the Armageddon Expo here in NZ - same thing though) where Christopher Judge was one of the guests)
In his stage presentation which was basically a Q&A with the audience, someone asked about his MacGyver appearance in the episode Live and Learn. Amazingly to me he recalled it quite well, he can still remember his whole role and character etc. To be honest I think he was impressed as well.

Anyway, he regaled us with how it all went down. He walked onto set he and RDA introduced themselves and they get into position for the huddle shot face to face. Action was called, cameras rolled and RDA let rip with a huge long fart causing the whole crew to break into hysterics. Everyone nearly wet themselves except Christopher, because he thought it was him!

That tradition continues on SG:1 where they had regular "gas" contests on set. I'm guessing baked beans was a staple diet.
The whole hour long season was highly entertaining. Christopher is a very funny and entertaining speaker and a great story teller.
After the presentation was over and he had left the stage I walked outside and he was standing over by one of the rails beside some small shed (with some other guy) wearing his heavy woolen trench coat puffing away on a cigarette. It was like no-one recognized him. I really wanted to snap a shot of him (because it seemed to humanize him and pull him out of the "TV star" persona) but I decided to give him some respect and privacy and didn't. It seemed really strange to me though to see this huge international TV star standing 10 yards away from all his fans and not being recognized - or maybe they also were respecting his right to a 5 minute smoke break before going back into do to a photo season.
I took a lot of photos and video clips, but non of them are very good because the lighting was pretty bad in there and I had to zoom the camera on my phone to get close ups, but here's the last part of him talking about the MacGyver episode - it caught me off guard, but some's better than non.