When the library attendant approaches Chuck demanding repayment of late fees and the shot cuts to show the Icelandic agent, suddenly the librarian has disappeared and the trio have changed positions.
As the Icelander walks towards Chuck, after having shot the professor, there is a close-up of his crossbow. From one angle, the string is in the forward position, having already been fired. When the angle changes, the string is pulled back, ready to be fired again.
In the pilot, Chuck tells a story about meeting Jill by picking up her books while running through the quad. In this episode, we see in a flashback that Bryce actually talks about introducing Chuck to Jill.
The number on the paper (219 F5U922) given to Chuck by Professor Fleming does not correspond to a Library of Congress Classification code nor a Dewey Decimal Classification number.
For the employee daily lunch schedule, Anna has no lunch hour while Leticia Williams has two lunch hours, one as a Buy More team member and one as a Nerd Herder. Morgan Grimes is listed as a Nerd Herd member rather than as a Buy More team member.
The minor character of "Fernando" (played by Jesse Heiman) is not listed among the Buy More employees on the lunch schedule board. Another minor character at the Buy More, "Skip" (Michael Kawczynski) who, similarly, had almost no lines during the show's run, is also not listed on the lunch schedule board. We see both characters during the episode, though. To be fair, it's possible that neither character at that time had a name.