Can I appeal a UAE civil judgment after missing the deadline due to travel?

It depends on the nature of the judgment. If the judgment was attended (meaning you or a lawyer representing you appeared in any of the hearings), then unfortunately it is not possible to appeal after the legal deadline has passed, even if you were outside the UAE. However, if the judgment was in absentia (default judgment) and neither you nor any legal representative attended any hearings, then you may still have the right to file an opposition against the default judgment, which would allow the case to be reconsidered before the same court.