theres also X wings & a tie fighter in Attack of the clones, as well as the flying cop vehicles (spinners I think they're called) from Blade Runner in either Phnatom Menace or AOTC..cant remember which off hand.

R2 D2 & C3PO are also to be found in Raiders Of The Lost Ark...they're represented as Hieroglyphics on the wall of the Well Of Souls, just behind the Arc.

In Indiana Jones & The Temple Of Doom the club theyr in at the very beginning is called Club Obi Wan.

Does this mean that all these films are connected in some way? that they all exist in some parallel universe?

Course they don't!

It's just a bunch of geeks having a laugh & sticking in things they find funny where ever they can get away with it for geeks like us to seek out & say "OOOOOOOOOOOOOOOOOOOOO, Cheeky"