Today I received an app rejection: 
 
"The marketing screenshots should not display placeholder images in the  iAd banner, per section 3.2 of the App Store Review Guidelines <https://developer.apple.com/appstore/resources/approval/guidelines.html>. Please refer to the attached image. You may choose to replace this image or remove it altogether."
 I hope the review continues fast after replacing the screenshots. I think theres hope cause the App Team wrote this:
"While your iTunes Connect Application State shows as Rejected, we don't  require a new binary.  Please visit iTunes Connect, Manage Applications  to replace the screenshots from all localizations, then reply to this  email and we will proceed with your application review."
So i think it won't take another week until the review continues.
  
Read this Article to avoid app rejections. Its a collection of rejection cases. 
Also check the Apple Guidelines for app aproval.