The pictures you took outside of the app, on your phone, will remain on your phone. The pictures you took in the app may or maynot stay on your phone. Sometimes Presto and MobiAudit make their own picture files in my camera app on the phone, I have recovered necessary pics from those files.
You should be able to back out of the app and check your photo file to see if there is a separate file, and look at the pics the phone saved to see if the pics you're worried about losing are there. That way you'll know whether or not it's safe to drive away and find somewhere with better signal or wifi.