In the first scene where Michael is using the cornballer and burns his hand, he's seen using a piece of ice in a rag to cool his burn. The piece of ice can be seen falling onto the counter out of the rag, but they continue filming anyway like it didn't happen.
The play that is being performed is William Shakespeare's Much Ado About Nothing. Tobias (David Cross) refers to Beatrice and Benedict, characters in that play, and a poster reads "Much Ado About Nothing Auditions." However, the lines that George Michael (Michael Cera), Steve Holt (Justin Grant Wade), and Maeby (Alia Shawkat) are shown reciting during their auditions are actually from As You Like It.
A list of Buster's activities uses the word "archeological"; this alternate spelling of "archaeological" may be considered wrong by some, but is typical of Webster's reforms and exists in common use.
When Lindsay first tries to get money from her mother for a dress, Portia de Rossi's native Australian accent shows through in her pronunciation of the phrase "Very nice, mom, I don't need anything."
When Michael burns his hand on the cornballer, George-Michael turns around, and his elbow hits the cornballer.