A short first flying phase from feet to hands makes it difficult to create an effective second flying phase from hands to feet. Short undercut first flying phases cause the hands to touch the floor with poor body angles to make a quick arms repulsion into a powerful turn over to the feet. Before bad technical habits get too engrained it is wise to spend time reviewing basic drills.
On the next few clips a different gymnast offers examples of some of those basic back handspring mistakes already mentioned. /Undercut with poor blocking repulsion and pike turn over. /A much longer and nice back handspring example with good hands to feet turn over. /Second flying phase example with an incorrect pike turnover.
Swinging both arms tilted to one side and twisting the body on that direction as if the gymnasts were trying to look over their shoulder to see where their body is going instead of keeping it square is another common back handspring mistake. Barrel back handsprings may help the gymnasts to work out the problem emphasizing to feel their backs landing on the barrell square and without turning the head sideways.