In the stoning scene, both man and woman are buried up to their necks. In a proper Islamic stoning (rajm), the woman should only be buried up to her waist.
When Amadou throws the spear at GPS, he clearly does not put enough force into the throw to puncture skin, especially not a cow's thick hide.
After the stoning scene, there is very little apparent injury to the victims. In reality, stoning is brutal, taking 10-20 minutes to cause death, and their heads would be completely covered with blood, bruises and wounds.
At minute 31:57 when one of the Jihadists is talking with Abu Alhassan on the mobile phone, the mobile phone's keyboard is seen on the screen, so they can't have talked on phone.