I've been mucking about with animated GIFs for a while now, but I've only come across these in the last two days.
The last two times I just manually flipped on the layers frame by frame to create the "Do Not Dispose" effect, now I have a much longer GIF and just telling Photoshop to "Do Not Dispose" all the frames isn't cutting it
What I think is happening is the original software is Not Disposing more than one frame, but Photoshop isn't capable of doing that.
For the comparison, note the cyan LED ticker in the middle, the smoke on the bottom left, and the light on the road when something is passing on the highway.
Original:
Photoshop output: