If you're interested only. I don't want people saying this thread is a waste of time, etc.
This hologram mistake takes place in the scene where Sidious first introduced Darth Maul to the viceroy. Now, Maul can be seen through Sidious' hologram. Assuming that Maul is standing behind Sidious, this will then be impossible. Only an object not part of the hologram projection can be seen through a hologram projection, as we all know. But Maul is part of the hologram projection as well (based on my assumption.)! If Maul can be seen through Sidious, it would mean Sidious really is translucent. But we obviously know that isn't the case, then how come we can see Maul through Sidious? I don't think I've explained this very well, though.
Of course, it is possible they're completely different holograms projected from different locations, but where can Maul be? We all know it is only in a later scene that Maul was sent to Tatooine, so, he should be with Sidious. But really, Maul in a different location is a little odd, since Sidious can't possibly assume Maul would go online and have a hologram projector at hand to have him appear at the right moment when Sidious said 'This is my apprentice, Darth Maul...'.
Well, they are Sith lords, and therefore very important. They most likely each have their own holographic thingamabobs, recorders. They're probably side by side, so they can each have their comfort zones. I meen, I'm sure they have the funding, and I don't think Sith like to share.