Flipping too slowly will scoop more water into the kayak, causing problems with balance at a later stage of the rescue.
Remount
A common mistake is not keeping your legs near the surface of the water until you complete your remount. Sinking your legs will result in the kayak being overturned (and thus taking on more water).
Scramble
A common mistake is lifting the head and upper body too high during the scramble, raising the centre of gravity.