Hela repeatedly states that she needs to track down Heimdall so she can use his sword to open the Bifrost bridge to expand her conquest. However, we have seen (in the first film) that Odin's golden staff can work the Bifrost just as well, and Thor is shown wielding it in the throne room, presumably meaning it was there the whole time. Hela may however be unaware of its use.
The goof items below may give away important plot points.
After Thor lands on Sakaar, his cloak gets easily and partially ripped off when he is fighting the gang attempting to capture him. A few moments later, when Valkyrie captures Thor and is dragging him to her ship, she is pulling him by his cloak that was earlier ripped off one shoulder, but is now inexplicably strong enough to drag him.
When Loki and Thor first meet up on Sakaar, Loki reveals that he's been there for weeks and yet despite this, Loki is somehow completely unaware that Hulk is also on Sakaar as shown by his reaction in the battle arena. This seems incredibly unlikely considering that not only is Hulk a huge celebrity there, but also that Loki had gotten in good graces with the Grandmaster. Surely he would have found out who the champion is. His likeness is even featured atop the Grandmaster's tower.