Quotes
Sheldon: Pleased to meet you, Dr. Gablehauser. How fortunate is it that the university has chosen to hire you, despite the fact that you've done no original research in 25 years and instead have written a series of popular books that reduce the great concept of science to a series of anecdotes, each one dumbed down to accommodate the duration of the average bowel movement. Mahalo.
Mistakes
Leonard has his phone on his left ear. Sheldon says "Since ears don't cross hemispheres..." This is an error. The vast majority of the input to the left (or right) ear crosses over to the opposite hemisphere. See more...
Trivia
Sheldon's laptop has gone through several strange transformations throughout the series, but in this episode it takes the biscuit - it appears to be a Dell XPS with the back covered up, but the shot of Sheldon chatting only to Amy shows that it's apparently running MacOS X. See more...
Movie Mistakes blog
Popular blog posts:
Top 15 biggest Harry Potter film mistakes
The 10 biggest mistakes in Iron Man 1 & 2
30 Biggest mistakes in the Star Wars movies
Other great sites
The Big Bang Theory (2007) - 30 with pictures
starring Jim Parsons, Johnny Galecki, Kaley Cuoco, Kunal Nayyar, Simon Helberg (add more)
Screenshots of mistakes that have been online for less than a year are only visible to members, but the rest are available to everyone. Don't forget to check out the picture of the day, updated daily, and the top 30 screenshots too.
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Updates: 
Series 2