According to a lengthy article in Vulture, director Joss Whedon's first cut of "Age of Ultron" clocked in at a lengthy three and a half hours. Whedon and producer Kevin Feige then had to whittle it down to 142 minutes. (Disney told us at a press screening the film has a 141-minute runtime.)
Nobody knows exactly which scenes were lost in the 68 or so minutes that were removed from the final cut.
However, one notable scene that we know was removed is one that may have predicted the arrival of Marvel's upcoming Black Panther character. The below, brief shot featuring a mysterious woman was included in the trailer, but not in the theatrical version of the film.
Marvel
A possible deleted scene from "Age of Ultron."
"We didn't want to introduce her fully-formed flying in a costume before you got to know who she was and how she came to be," said Feige.
The final "Age of Ultron" runtime is lengthy, but still not that long when compared to other popular summer blockbusters. For instance, "The Dark Knight Rises" clocked in at 165 minutes.
In fact, "Age of Ultron" is even shorter than than the first "Avengers," something which Joss Whedon surprisingly envisioned but thought would never actually happen.
"I said to [Marvel Studios President Kevin Feige] before we started, 'My secret fantasy that'll never come true is that the second one is shorter than the first,'" Whedon said, "and we're shorter by a minute."