The GBA Version has a hub! It's the Cantina like the console counterpart, and that's about it. There isn't much to do here. The Episode doors are here leading to the levels. But really, aside from that it's just the Cantina Bar to buy Hints, Characters and Extras.
Unlocked Characters: Princess Leia (Senator), Rebel Trooper, Probe Droid (500), Slave I (50,000) [These Two are only if the Extra Vehicles Extra is bought]