When Charlie tears the bar code off of the box of pears, most of it is removed. Seconds later when he shows it to Don, only about half the bar code is missing. This would actually leave enough of the bar code to be scanned correctly.
Charlie tears only the UPC bar code off (the one with just straight lines); he leaves the QR code (the smaller, speckled image above the UPC code). The QR code could contain all the information he describes to Don and includes the information in the UPC code.
One of the FBI agents checks the pulse of a man who had clearly been electrocuted, before first disconnecting him from the car battery and making sure she was insulated from any remaining charge or current.
When Charlie checks Emerson's math skills, he asks for the square root of 7. The correct answer is 2.64575131106, but Emerson says 2.645751311106 (a superfluous '1').