Hi there @lif-ab,
Thanks for posting in the Community!
Any changes you make to the content of the Emails within your Flow will apply to anyone who hasn't yet received that message (even those Profiles who are already in the Waiting queue or Needs Review queue.) So for example, people who are scheduled to get your Email tomorrow will receive whatever the email looks like at the time the email is sent. Updating your images in your live flow will not interrupt sending to your customers/users. It will continue sending the previous version until you have saved your changes and then all future sends will reflect the new images.
Hope that helped!
Alex
Thanks Alex, huge peace of mind!