Time scrubbing is an extremely important ability in the game, however it has two significant shortfalls.
1. You can't scrub forward and view the intelligence screen. Sometimes I want to know how much neptunium per hour I will be earning in 10 hours time, or how much player 2 will lose per hour when I capture his outpost.
2. If a sub is launched and I can see it, then proceeds out of sonar range, it would be great to have a 'ghost' of that sub remain on screen until it either arrives at its destination or comes into sonar range again.
I understand things like sub to sub combat or certain specialists can affect subs before arrival, but the ghost would only react to Intel that you know, rather than the system just 'forgetting' about the sub because it is off sonar.