The script was changed by the sponsor at the last minute today; how can I avoid version control chaos?

A sponsored video script was changed by the client in three places just two hours before filming today. Filenames like 'final', 'final2', and 'newfinal' had already started appearing in the team chat. I stopped everything to consolidate the version into a shared document, turned on 'track changes', and highlighted the mandatory compliance lines in red. During the shoot, we only followed…