When Steve Coogan makes his plan to rob the bank on his "Tasks for today" board, you will see that for the lifts in the centre of the lobby, he draws a pretty straight-sided square with the top left corner missing. He also shows stairs by drawing another line parallel to the bank wall, with three pretty equally spaced lines in between.

Later in the film when Kirsty is stealing his TV, it shows the "Tasks for today" board again. This time the lifts section has a lot rounder sides (the top left corner is still missing though), and the stairs are drawn as a line parallel to the bank wall again, but this time the inside lines are differently spaced. Two a close together and are both further away from the third one.

I reckon they probably shouldn't have rubbed off the first version of the plan between takes. That way they wouldn't have had to draw up another one.