Continuity mistake: When Bella Donna is being selected as the chosen one for the Guild of Assassins, she is flanked by three of her guild members. When the shot changes, the three guild members have disappeared. (00:06:49)
Continuity mistake: When Wolverine enters the infirmary, Cyclops is resting his right hand on his lower abdomen area with his fingers extended. When the shot changes, his hand is a closed fist and has moved closer to his chest. (00:07:37)
Continuity mistake: When Wolverine runs up to Gambit's mini-jet, he puts a considerable amount of distance between himself and Jean Grey, and nearly makes it all the way to the jet and Rogue before the shot changes. When the shot does change, he is suddenly several feet back from where he just was, and Jean Grey is now right behind him. (00:09:01)
Continuity mistake: When Bobby and Pierre enter the basement of the Thieves Guild's mansion, Bobby is on the left, and Pierre is on the right. When the shot changes, they have swapped places. (00:12:43)
Continuity mistake: When Pierre is telling the Assassins that they betrayed the Thieves, he raises his left arm and points his finger at them, and then lowers his arm back down. When the shot changes, his left arm is raised again. (00:15:00)
Continuity mistake: When Bella Donna is saying the Assassins are prepared for the tithe, a man with long green hair is behind her on her left. When the shot changes, he appears to be standing between her and Gambit. When the shot changes again and Bella Donna is stroking Gambit's hair, he is nowhere to be seen. (00:14:16)
Continuity mistake: When the Danger Room doppelganger of Omega Red confronts Cyclops, its left arm is pointed down. When the shot changes, its left hand is raised at almost shoulder level. (00:03:01)
Revealing mistake: When Bella Donna is preparing to shoot a blast of energy at Rogue, her body passes through the left hand of the man on her left that was holding her back. Half of her cloak then disappears as she strides forward. (00:14:42)
Continuity mistake: When the External selects Bobby to be the chosen one for the Guild of Thieves, she turns his jacket red and his gloves gray and fingerless. When he is shown again a few shots later, his jacket is now green, and his gloves are brown, with only the thumbs being fingerless. (00:06:53)
Continuity mistake: When Gambit is saying "You got me in the guild, Bobby," you can see on the wall across the hall that there is a switch that is the same red color as the wall. A few shots later, the switch is now gray. (00:10:18)
Continuity mistake: When Jubilee is heading to the store, the driveway of the mansion is shown to have a roundabout by the front door, and a small path leading to the front gate. However, the previous episode 'Til Death Do Us Part: Part 1 showed the driveway was a winding path longer than what is shown here, and there was also no roundabout. (00:06:04)
Continuity mistake: When Xavier and Magneto are trying to escape from Vertigo, Xavier cuts the ropes of the bridge they are on, leading him and Magneto to swing into the cliff wall and hop down safely to a ledge below. When they look back up at Vertigo, she is at roughly their 10 o'clock, with the other side of the bridge by her feet. Considering that they just dropped down onto the ledge and have only moved a couple steps to their left, the other side of the bridge should still be directly across from them. (00:15:45)
Chosen answer: It says MPO "First Exemplary Printing House" which is a real printing company in Russia founded by Ivan Dmitrievich Sytin in 1889. There seems to be something about "named after..." as well.
Sierra1 ★