Like any major undertaking, it's difficult to completely avoid mistakes in a book. Here are the ones that I know about. If you find any others, please let me know so I can correct them here.
page 77, understanding hydraulics: there is one major error here that needs to be corrected. I stated that when calculating braking force, you take the area of all the pistons in a caliper into account. This is incorrect. The area of the pistons on one side of the caliper should be taken into account. In other words, a two-piston caliper with opposing pistons will provide the same braking force as a single piston caliper if the pistons are the same size. There are also some mixed-up units and terms when referring to pressure and force. Yes, I'm very embarassed.
page 102, photo of drilling the fuel tank: This picture is printed sideways. You might not notice but it sure looks odd to me.
page 160, middle picture: The wrong picture managed to sneak in there somehow. It should be this one.