The Electric Can Opener Fluctuation - S3-E1
Continuity mistake: Sheldon's Sandwich goes from looking burnt to not burnt in the next few frames. (00:16:56)
The Cooper-Nowitzki Theorem - S2-E6
Continuity mistake: When Raj says there is always a catch, Leonard's hand goes from on the table to on his leg between camera cuts. (00:03:00)
The Griffin Equivalency - S2-E4
Continuity mistake: When talking to his parents, Raj's grip on the laptop changes between shots. Note the side of the screen. (00:18:10)
The Barbarian Sublimation - S2-E3
Continuity mistake: When Penny is talking to Sheldon in his bedroom, her hands are constantly changing positions between shots. (00:08:45)
Continuity mistake: When Sheldon is looking at his socks that Penny paired up, his grip on them changes between shots. (00:06:00)
Continuity mistake: Penny throws Sheldon's sock down on the table, and their positions change when Sheldon picks them up, despite no one touching them. (00:05:50)
Continuity mistake: When Leonard shows Penny the leaflet at the end, she is holding it in one hand in shot but with 2 as the camera changes. (00:19:50)
Continuity mistake: Leonard says that Sheldon has gone crazy and chucks his pen down on a red pad on the desk. When the shot changes, so does the position of the pen without being touched. (00:13:10)
Continuity mistake: In the laundry room, Sheldon is holding a blue shirt in his hands and has a bit of extra material near his hands. When the shot changes, he is holding the shirt differently and the extra material has gone. (00:05:50)
The Extract Obliteration - S6-E6
Continuity mistake: Sheldon is sitting by himself at a lunch table with an opened bottle of water with the bottle cap in front of the bottle. Raj and Howard arrive, and in one of the shots, the bottle cap moves closer to the bottle by itself.
The Grasshopper Experiment - S1-E8
Deliberate mistake: At the end, Penny holds up a bottle of rum to show Leonard that she added it to his drink. However, the B is missing from the name "Bacardi" (00:19:30)
The Big Bran Hypothesis - S1-E2
Continuity mistake: At the very end of the episode we see Penny with her hands on the corner of the piece of wood. Camera cut and now they are in the middle. (00:19:50)
The Big Bran Hypothesis - S1-E2
Continuity mistake: When cleaning Penny's apartment, Sheldon is holding up a jacket. Camera cuts and he is no longer holding the jacket up. (00:09:50)
The Big Bran Hypothesis - S1-E2
Continuity mistake: When Sheldon says the line about having no peers when cleaning the apartment, there is a pair of jeans on the side which disappears when the camera cuts. (00:10:00)
The Big Bran Hypothesis - S1-E2
Continuity mistake: When Sheldon is cleaning, he moves an iPod dock and the iPod lights up. Camera changes and the iPod is unlit. A few shots later it's lit again. (00:09:00)
The Big Bran Hypothesis - S1-E2
Continuity mistake: When shifting the box along the floor of the 3rd floor landing, Leonard's grips on the box is constantly changing. (00:06:00)
Chosen answer: The song is called "Dark as a Dungeon" and was written and first performed by singer-songwriter Merle Travis in 1946. It has been performed by a wide array of artists, including Tennessee Ernie Ford, Harry Belafonte, Dolly Parton, Queens of the Stone Age, Kathy Mattea and Amy Grant. But it was made most famous when it was performed and recorded by Johnny Cash during his concert at Folsom Prison in 1968. According to Wikipedia: "It is a lament about the danger and drudgery of being a coal miner in an Appalachian shaft mine. It has become a rallying song among miners seeking improved working conditions."
Michael Albert