Due to scheduling conflicts, Morgan Freeman and Gerard Butler don't appear in the same scene together in person. The scene in the hallway at the White House uses body doubles, and doesn't show faces.
Olympus Has Fallen (2013) director Antoine Fuqua refused to direct this sequel because he didn't like the script.
The jogging sequence at the start of the film, was filmed in Kensington Gardens in central London.
Throughout the whole series, Gerard Butler toned down his Scottish accent since his character is American. Notably, in scenes with fellow Scottish actor Bryan Larkin, Butler's accent returns. This is actually a common linguistic phenomenon and generally happens unconsciously; people with multiple accents will generally conform their own accent to match whoever they are talking with at the moment.
Oddly, even though Angela Bassett only accepted her role in the previous instalment to work with Morgan Freeman. In this instalment, she did not work with him at all, their characters share no scenes and never interact.