Well, never let it be said that Michael Bay and his team do not strive to make the best of a bad situation.
In Transformers Revenge of the Fallen, star Shia Labeouf was involved in a nasty car accident which needed him to have his hand in a support for part of the filming. It was written into the film by way of a “Spacebridge accident”.
However although earlier reports suggested the process would repeat itself and Monday’s Bumblebee crash on the Transformers 3 set would be written into the film, this has since proven to not be the case. Nelson posted on the Shoot for the Edit forums to dispel the reports the accident would be written in.It’s not going to be written into the script for the sake of decency. You don’t put accidents into your movies, not kosher.
Besides, they have a backup BB.