Most of the camera/positioning discrepancies are because Floyd was detained on one street and then physically walked to another mid-arrest. The rear view footage came from another officer's vehicle. In the full video, that officer can be seen briefly walking outside that vehicle, and otherwise re-positioning the vehicle as the scene evolves later.

Beyond that, it's likely the officers soon believed--after Floyd was put into the distant police car--that he was experiencing excited delirium. This is why they called an ambulance and Floyd was removed from the vehicle. This also explains why he was restrained by multiple officers at once, which is standard for that scenario. (Notably, they aren't supposed to hold the overdosing victim on his stomach but his side, though that isn't always possible given the state the person tends to be in at the time.)

This also explains why he was held on the open street instead of on the sidewalk -- he was difficult to handle and would have been rapidly overheating. Increased struggle and movement accelerates overheating and, by extension, death. Therefore, their goal is to get the person out, restrained and totally immobile as fast as possible, and then sedated at the earliest opportunity.