Aren’t those lamp oil (fire) barrels? Those won’t count as valid barrels in the cart. You need explosive barrels. There are only 3 explosive barrels outside of the cart event and they spawn in fixed places.
This is because there is an Okri’s Challenge in Empire in Flames to not use any of the event-spawned explosive barrels, requiring the team to carry an explosive barrel from the start.
Only the last barrel is in your post.