Days of Future Past: Part 2 - S1-E12
Factual error: When Gambit is inside his mini-jet after escaping from Bishop and Wolverine, his radar screen says "Washington D.C." but the graphic above it is Washington state.
Factual error: Batman is in Japan and tracks down Kyodai Ken by using Caller ID, which returns a seven-digit "555" number. Telephone numbers in Japan have 8 digits.