Thor: Ragnarok - 12 Major Reveals From The New Images
4. Has Thor Been Here A Long Time?
It had been assumed that Ragnarok would pick up with Thor back on Asgard, dealing with Loki's deception and attempting to restore order while he looks for more information on the Infinity Stones, but there's something about Thor's look that suggests he hasn't been home in a long time.
His beard is longer, he's cropped his hair (probably to better suit battle) and he's completely changed his look, it's not like he's just rocked up to Sakaar and suddenly had a make-over. Perhaps he's a prisoner of someone else - Gladiator style - before he's dumped on Sakaar and comes face to face with the Hulk again?
Though Taika Waititi released the two comedic shorts filling in where the God Of Thunder was during Civil War, it wouldn't at all be surprising if that was just misdirection, and the reality is that Thor never made it home. That would allow Loki to still be on the throne of Asgard (and not in a hole of Thor's making) and it would allow the film to focus away from the Infinity Stones, since they're presumably not going to be the primary focus here.