The Soviet naval ships are shown flying a red flag with a large yellow sickle and hammer in the center. The Soviet naval jack was red with a white cross on the diagonal as well as from the center, a blue diagonal cross was superimposed on the flag with a small white sickle and hammer in the center.
The General in the War Room mistakenly calls upon the mobilization of the 7th Fleet to intercept Soviet ships bound for Cuba. It was the US 2nd Fleet that intercepted the Soviet ships during the Cuban Missile Crisis. The 7th Fleet is and has always been, based in the Pacific (currently stationed out of Yokosuka, Japan).
Magneto finds out that Sebastian Shaw is hiding in Argentina, in "Villa Gesell". When the scene takes place there the camera shows a view of mountains and snow. Actually "Villa Gesell" is a town on the beach in Argentina (no mountains there). The image shown on the picture looks like Bariloche, which is in the mountains and has a large German community.
The following FAQ entries may contain spoilers. Only the biggest ones (if any) will be covered with spoiler tags. Spoiler tags have been used sparingly in order to make the page more readable.
Q
Why is Emma Frost in both "X-Men Origins: Wolverine" and "X-Men: First Class"?
A
Bryan Singer stated they did their best to remain in continuity with the other X-Men movies, but he recognized that some liberties were taken for the sake of the plot in X-Men: First Class. Lauren Shuler Donner also stated that the Emma Frost in X-Men Origins: Wolverine is not Emma Frost, but the real Emma Frost is the one in X-Men: First Class. Furthermore, the credits in X-Men Origins: Wolverine list her as Emma/Kayla's sister and not exactly Emma Frost. So, while X-Men Origins: Wolverine initially advertised the character with diamond powers as Emma Frost, Fox technically retconned her appearance in X-Men: First Class by ignoring her appearance in the Wolverine movie and stating that the character wasn't Emma Frost. Source
Q
How many "X-Men" movies are in the "X-Men" franchise?
A
There are four other X-Men movies: (1) X-Men (2000), (2) X2 (2003), (3) X-Men: The Last Stand (2006), and (4) X-Men Origins: Wolverine (2009). X-Men: First Class leads to X-Men: Days of Future Past and a scheduled third installment of a planned trilogy. If The Wolverine is considered part of the franchise, it makes movies seven total.