See, it's just a reflection...
points to the holographic "Gallery of Star Heroes" in a long forgotten corner of the bar, now a little unsafe because of the mutant GreenyBlue®©™Rat problem in that area.
The Slug hologram was malfunctioning, flickering on and off as though it wanted a drink...
...casting a reflection on the bar, which because it's a hologram is in 3d.
Logical explanation for everything

