Watch the scene more closely

You'll see that Bob was backhanded by Killabyte and knocked out -- he was unconscious when Killabyte upgraded to Gigabyte and was sucked into Mainframe. By the time Bob regained consciousness, got Glitch and got to Mainframe, Gigabyte had already been torn apart into Megabyte and Hexadecimal. At no time did Bob actually see Gigabyte.

As for the mysterious Guardian icon, I'll ask Joxer about it but I'm pretty sure it was just another colouring goof. The quality of S4 wasn't up to Gavin's standards and yes, he's miffed about it. Its not that the goofs weren't caught during editing: They were, but the Higher Powers pulled the old "We don't have time to fix them" card on him and he had to ship out an inferior product with sloppy flames, miscoloured icons, permeable dashboards and got-dressed-in-the-dark AndrAIa and Hex still intact.

Is mise le meas
-==- Katzedecimal