In the episode where Lucy tries to do a burlesque skit, while she is practicing, you can hear Ricky's distinct laugh (It sounds like Oh-Hoah Hoah! Oh hoah hoah hoah!). How was Ricky able to see this when he's at the Tropicana club?
This is because the show was rarely filmed in front of an actual audience, so they had to play "laugh tracks." If you listen closely to other shows you will hear him laugh when he is not in the scene.
Actually, the show was almost always filmed in front of a live audience; it was one of the groundbreaking shows of the '50s in that they filmed it on film in front of a studio audience. (Lucille Ball also acted better in front of an audience.) What's more likely is that Desi Arnaz was watching the filming offstage, possibly in the audience (because they installed lots of mikes over the audience's heads to get an authentic laughing sound) and the mikes caught his laughter.
Ricky was watching the skit and couldn't help but laugh at Lucille's comical antics. If you listen carefully you can hear his laugh in a few other episodes too. He just thought Lucy was that funny, which she is!
Actually everyone here is right, live audiences were often used on the I Love Lucy show. However, tapes of laughter were used when the audience didn't respond as well as hoped by the writers and producers. Both of the points made here were possible.
In many of the I love lucy episodes you will definatly hear Ricky and also another woman who always goes,"uh-oh hohohoh" sort of like that...listen, I'm postive you'll hear her.
This show was always filmed in front of a live audience. They use a process called "sweetening," which is using a laugh track if the audience doesn't laugh at the designated time. It is fairly obvious, because there's a few of the same laughs in many different episodes. They only didn't film in front of an audience if they were doing one that involved Little Ricky in most of it.