I heard that you can't daven in front of a picture
What does this included?
A mogen Dovid?
A flag of israel?
What if it is part of the paroiches or Aron kodesh ....
The Ramma in siman 90 siff 23 explains the reason not to pray in front of pictures is because it distracts one from concentrating.
This is the same reasoning The Mishna Berurah there uses to explain the Mechaber.
So in fact any picture that distracts, such as one found on clothing as the Mechaber mentioned, are problematic.
The Mishna Berurah also points out that praying in front of a mirror is problematic both because it looks like one is praying to the reflection, and because it is distracting.