2 Issues

Here is my multiplayer tank game (so far)

2 issues.

First: There seems to be an extra tank in the top left hand corner. Anyone know why it is there and how to fix it?

Second: I want there to be shadows in the game, to add some depth, but I only want shadows to be cast from the tank that you are controlling, not all of the tanks.

Any suggestions?

You should provide a copy of your project for investigations as what you are currently asking for is a crystal ball prediction.

For the top left tank on the peer screen, possibly are you having a tank instance in your layout by default that does not get destroyed on start of layout on the peer side.

If that object has the "bound to layout" behavior, that is a common thing that may happen.

For the light cast, hard to say without the hands on the project.

Also, the casting behavior is possibly not designed to be used over multiplayer to be used as fog of war.

You'll possibly have to make a render on your host, and then pass it on to the peers so they display it in the same vein through multiplayer messages.

sorry just not sure how to upload a cp3 file here yet

Upload your file to an hosting service, provide the public link to it.