kotor box
 

look at the back of the kotor and TSL box some the pictures on there are impossible.

It is actually very possible. I don't know if you know this, but you can warp to different modules at any time using the cheat console.

What about bastila fighting dark jedi on taris?

It's quite easy to spawn an NPC. They wanted it to look interesting, so they added a Dark Jedi on taris using scripting, then quickly erased it. Anything is possible with modding :p