When Michael rips up his signed pledge, Jim is chewing on a pencil. When the camera shows Jim again, he is chewing on a pen.
When Dwight hangs up Jim's sales call, you can hear the dial tone. Since Dwight's finger is holding down the switch hook, there would be no dial tone.
On the index cards that Michael has everyone put on their forehead you can clearly see 'Meredith' written on the back of Meredith's card while she is talking to Dwight.