Other mistake: Towards the end, Chewbacca and Beckett have walked some distance from the landed yacht. They come up a small slope and are faced with Han, waiting for them. But an aerial shot shows that slope is very short and just runs down to a cliff. There's no way they could have got to the base of the slope to walk up it in the first place.
Revealing mistake: When Chewy puts his hand on Han's shoulder at the end, Joonas Suotamo's finger is visible through the fur.
Continuity mistake: When Lando is rushing over to L3's body, the white panels behind him in the Millennium Falcon pop off from the battle and turbulence. It quickly cuts to another shot where they are still attached to the wall. (01:27:15)
Other mistake: Apparently, the route to Kessel is the same no matter from which direction or part of the galaxy someone needs to get there.