Thomas & Friends: Big World! Big Adventures! The Movie (2018) on Netflix

Plot summary

On Sodor, the tank engine Thomas wants to travel the whole world, the first steam locomotive to do it. Ace, a rally car on his way to a race that begins in Africa, stops on the island and talks Thomas into coming along. Thomas asks Sir Topham Hatt for leave, and Hatt, distracted by a telephone, unknowingly gives it; Thomas is loaded onto Ace's ship at the docks. In Dakar, Senegal, they head into the Sahara for the first race, where the tracks end and Ace leaves him behind. Thomas takes on a line of rolling stock bound for Dar es Salaam, and at a train yard meets Nia, an orange tank engine; her offer of help he turns down, and she follows him anyway. Sir Topham Hatt, meanwhile, reaches Senegal and crosses the desert by camel looking for Thomas.