Land of Black Gold: Part 1 - S2-E10
Revealing mistake: Tintin sees the four men planting the explosive in the pipe line. Two of the four men are kneeling beside the pipe, one on the front side wearing a brown cloak and green clothing and one on the opposite side wearing grey clothing planting the explosive in the pipe. The man on the opposite side in grey clothing is passing through the pipe when the two are first kneeling. (00:12:20)