When the pair arrive, Smoke explains that the Vagos and San Fierro Rifa are "cutting some kind of deal," and intends to crash the meeting. However, it is actually an ambush and the Vagos attempt to escape by train. Carl and Smoke use a Sanchez parked nearby, to chase down the train to kill all four Vagos thugs, whilst avoiding obstacles such as; oncoming car blocks and incoming trains going the opposite direction. If successful, Carl and Smoke will have eliminated all Vagos before the train reaches the Frederick Bridge, connecting Los Santos and Las Venturas. The two then clear the scene, and CJ takes Big Smoke back to his house.
In order to complete the mission the player must:
Drive to Unity Station.
Get on the motorbike with Big Smoke, chase down the Vagos gang members and take them out!
Keep up with the front carriage of the train so Big Smoke can shoot the Vagos gang members.
You left You left Big Smoke behind go get him! (if Big Smoke falls off the Sanchez.)
Follow that train! Get me close, CJ. I'm about to pop these fools. Roll up on them CJ, so I can get a shot! Oh fuck! An on-coming train! Take the high road on the right, CJ! Look the fuck out, CJ! The train! Move this shit, man I'm gonna ice these fools, man.
If the player fails the mission by losing the train, Big Smoke will shout "All we had to do, was follow the damn train, CJ!". Due to the difficulty of the mission, leading to many players failing it multiple times, this line became very famous among fans of the Grand Theft Auto series, to the point of becoming an internet meme.
In the open-world sandbox game Minecraft, there is a splash which reads "Follow the train, CJ!", which is a reference to this mission.
Even if the player kills the train driver before entering the red marker on Unity Station, the train will still depart from the station during the cutscene.
It is possible to use Big Smoke's Glendale to chase the Vagos, however this is not recommended as the Glendale can barely handle off/road well as the Sanchez and it is too big and it could be prone to being hit by a train if in a wrong area.
In the beta version, when chasing the train, CJ would complain that the bike wasn't built to take so much weight, and claimed that people don't call Big SmokeBIG Smoke for nothing, to which he angrily replies that he was born big, as seen in this video.
Also in the beta version, another objective would have been to retrieve a package from the dead Vagos, as seen in this video.
This is one of the first missions to take Carl out of Los Santos and into Red County.
If the player abandons the Sanchez after killing the Vagos, it will still appear in the mission's final cutscene.
Strangely, if the player fails the mission just as the Vagos crosses the bridge and looks closely, the player will see that the train will pass through a barrier as if it weren't there.
This mission is referenced in the Gold-medal objectives for the Grand Theft Auto V mission Derailed, where the player has to follow a train on a dirt bike. If they manage to land on top of the train on their first attempt, they will achieve the "Better Than CJ" objective.
If the player fails the mission within close proximity of the moving train, all of the Vagos on top of it will become invisible. Their weapons will remain visible. The first three Vagos will be explosion-proof. The fourth Vago is fully-immune, and can't be killed.
If the player manages to kill all the Vagos before the train hits the broken down Glendale, the car will not explode when the train hits it as scripted and will simply be pushed away by the train.
It is possible for the second and fourth Vagos from the front of the train to mysteriously die, leaving only the first and third to kill. If driving correctly, they can be killed before meeting the oncoming train in the tunnel. The player can see their guns land on the tracks if looking back quick enough (tested in PS4 version).