I was watching my Lucy-Desi comedy hour DVDs recently and noticed something odd in "Lucy Goes To Mexico." There is a long stretch of the episode where there is no laugh track. It starts around the time Lucy and company arrive in Mexico until the sequence at Ricky's rehearsal. Given how heavily this show utilized the laugh track, it seemed very obvious that it was missing. Anybody else notice this?

Yes, I have noticed that, and on a video I have of this episode taken from a 16mm print years ago it is the same in that version, too.

You bring up a good point, is it me or is it that you can tell in some episodes of the hour shows when canned laughter is used and when an audience is present? In the Milton Berle show it seems like it is about 50/50, the one where Lucy wants a career seems to have been filmed in front of an audience, and the Summer Vacation and Japan shows are all canned. Of course, some of the scenes filmed like a movie do not match with the rest of the episode as the lighting, make-up, etc. are way different than other scenes.