For the “bill” itself, we can’t see the other side, but there’s enough differences that you wouldn’t mistake it for real currency at more than a glance. Fake bills for movie/tv sets look far closer to real bills (basically with obviously fake serial numbers and “for movie use only” stamped on it.

For leaving it as a tip, it’s not being used to satisfy a payment. While tipping is expected, it’s not required and there’s not an agreed upon amount between the parties. So they’re just leaving a scummy flyer behind. Not any different than the people that ‘tip’ with Chick Tracts. If they were to use it to try and pay the bill, it’d be illegal.

Maybe, but also only if it’s trying to be used as cash. Trying to pay for groceries, meal, depositing it at a bank, etc. would be an issue. Leaving it as a tip, while a scummy thing to do, isn’t on the same ballpark since it’s not an agreed upon transaction (i.e. no price for a tip is agreed upon by the parties), and you’d have to prove intent to pass it off as cash and not just a flyer/pamphlet.

You still use the carrier sim card for a connection. That doesn’t depend on what OS you’re using.