Branch smashes his party invitation and walks away without taking it but then is later seen with the invitation in his bunker.
When the king says "hug time," while in Branch's secret lair, he has all his clothes on. In the next shot he is only wearing his underwear.
When Branch and Princess Poppy are waiting inside Branch's bunker we do not see the lever. But in next shot Branch pulls the lever down and they go under the bunker.
When Chef takes the trolls, we do not see her snatch DJ Suki. However, DJ is seen in the fanny pack chef is wearing and later in the cage at Gristle's castle. Chef also takes 3 random trolls that we do not see in the cage at the castle. Poppy does not mention DJ as one of her friends to save when pleading with Branch in his bunker, but speaks of her every seen after.
When Creek confirms to Poppy that he is selling out all of the trolls, he suggests he made the deal immediately after being nearly eaten. Because of that, there would have been no reason for King Gristle to have Creek in the locket during the date scene. (It's more likely Creek would have been helping Chef find the other trolls.) Unless Chef had planned have Creek in the locket to lure Poppy to a trap.
When Bridget sees herself in the plate, the reflection is not a mirror image (her front tooth should have been on the opposite side).
Chef puts the trolls in a cage. The spaces between the bars are larger than most of the trolls. They could just walk out, open the latch, then all escape.
When they discover Creek is still alive, Poppy, Branch and the other Trolls should have suspected about it instead of being happy about it and trying to rescue him, which led them to be captured by Chef.
When Cloud Guy is talking to Branch he insists upon a 'high five'. Cloud Guy and Branch only have four digits on each of their hands.