When Wesley receives the piece of cloth with Sloan's name on it, before he actually writes down the binary code on the glass table with the marker, you can see that its already written. But when he starts to write down the code, the table is clear again.
In the office at the end of the film a nameplate is visible on one of the cubicle walls. The nameplate reads "J.G Millar" which is a composite of writer Mark Millar and artist J.G. Jones, on whose comic the film is based.