Iron Man 2 has the 99 track issue found on some other high-profile movies, however, the movie converts just fine, if you select the correct track.
When DVD Catalyst 3 brings up the track selection dialog, it automatically selects the track with the longest playlength, however, in the case of Iron Man 2 (at least the 3-disc bluray+dvd bundle) the track you should use is actually #40
If you are not sure what track to pick, just play the DVD on a DVD player or in Windows Media Player, and look at the LCD display when the movie is playing (or in WMB at the top left if you mouse-over the video) for the correct track number to use.
Other than that, there are no conversion issues with Iron Man 2 and DVD Catalyst 3
