When Henry and Thomas leave Tidmouth Sheds together, Henry's wheels are moving backwards. Additionally, Henry is still laughing, even though his mouth has stopped moving.
Thomas' London, Brighton and South Coast Railway number is 70 to commemorate the 70th anniversary of the Railway Series, but the E2 numbering ran from 100 to 109. Also, Thomas would have likely been painted in the LBSCR's Marsh umber livery (a dark brown) and not teal.
When Edward says "It's not as easy as you think, Thomas!" the points he's going over are against him and a crew member's hand is emerging through the wall of Edward's cab.
In a close up of Gordon as James goes past him, James' tender is in his red livery.
This movie shows Thomas going to the Steamworks, even though it wasn't introduced until the events of Thomas & Friends: Hero Of The Rails. The same mistake was made when Sir Topham Hatt told Thomas to take James to the Steamworks.
Henry was not in his original "pre-Flying Kipper crash" shape, even though that the events of TAB take place before those of The Flying Kipper.
In the 1st season of Thomas & Friends, James was wearing his red livery when he crashed. But in this movie, he was wearing his original black livery when he crashed.