Alright, just did some slo-mo DVD work and got an answer from a friend on the inside.
After the Kamino battle scene, Jango does get the dent from the door of Slave I. However, the mistake that was made by ILM, is that the dent does not stay consitently in the same spot. The door dent was on Jango right hand side of the helmet. This is consistent with the dent seen when Jango captures Anakin in the droid factory. The change comes once they hit the arena, the dent moves from the right side to the left side at the top of the helmet. It stays like this for the rest of the shots. My source says that there is a chance that it will be corrected for the DVD, but it is not a top priority. Apparently they like to leave little things like that in sometimes.
On another note, I just noticed this today, slow-mo style...
When Mace cuts off Jangos head, in the shot where it shows Jangos helmet hitting the ground, just before the helmet enters the shot, there is one shadow that separates into two shadows. One shadow falls off screen, the second follows the helmet to the ground.
Hence, Jango head came out of the helmet before it hit the ground.
Alot of good that gasket did...