CNN screenshot of woman saying she heard ..allahu akbar..."
From the UK Daily Mail, notice that Witnesses is plural:
"Witnesses said that the shopping centre gunman screamed 'I'm German' and 'Allahu Akbar' before shooting"
http://www.dailymail.co.uk/news/article-3703705/Major-police-investigation-way-shots-fired-shopping-centre-Munich.html
"A woman named Loretta said she was in the McDonald's when the man with a gun came out of a bathroom and began shooting.
She told CNN: 'I come out of the toilet and I hear like an alarm, boom, boom, boom. He's killing the children. The children were sitting to eat. They can't run.'
Loretta said she had been in the bathroom at the same time as the shooter, with her eight-year-old son. She said the man yelled: 'Allahu Akbar!'"
What other named witness has given any account as detailed as that?
Plenty of mozlems in Germany are “German”, so that really means nothing.