This special was a collaboration between many artists in order to celebrate (or perhaps mourn) the end of Ultimate Marvel Team-Up. However, many of these artist both pencilled and inked their work. To keep things simple, only the artists who inked exclusively are credited. For future reference, the pencillers who didn't ink their art were: John Romita Sr., Mark Bagley, Jacen Burrows and Leonard Kirk.
This issue's continuity is up in the air. Because various characters (Elektra and the Fantastic Four in particular) appear in ways that conflict with their incontinuity selves, it may be safe to consider it out of ultimate continuity.