It Wasn't Meant to Happen - S2-E20
Continuity mistake: While Susan and Edie are at the Hooters style restaurant, the amount of beer, and amount of head, in Edie's glass changes from shot to shot.
There's Something About a War - S2-E13
Continuity mistake: When Lynette and Tom are talking, Tom says "Really I got the job?" and puts down the newspaper he was just reading. In the next shot we see Lynette and you can see Tom is still holding the paper and puts it down again.
There's Something About a War - S2-E13
Continuity mistake: As the nurse is talking to Susan about the operation, the folding of the paper the nurse is holding on the clipboard changes between shots. First it is half folded over, the next shot it has been folded right over and is being held right down. After this shot it changes again and is now folded back without her moving the paper.
Answer: He was investigating the lead not the case.