Fact: Avi and Rand were in the Southern Hemisphere of Seanchan in that FoH igloo scene. RJ confirmed this in Q&A, once. I can dig up the quote, if needed.

Assumption: Avi and Rand were on the eastern edge of the Southern Hemisphere. When Rand woke up, he watched the sun rise over a "vast ocean", which must have been the Aryth Ocean.

Fact: According to the Guide, the eastern edge of the Southern Hemisphere of Seanchan is about half way around the world from Cairhien (where Avi's gateway originated). So, about 12,000 miles = ~12 1hr time zones to the West (as looking at the map in the Guide). The earth is 25,000 miles in circumferance, and the day is 24 hours long, so each 1 hr time zone is slighly more than 1000 miles wide, at the equator.

Fact: When Avi and Rand left the igloo, the sun was just rising. This was specifically stated in the scene.

Fact: When Avi and Rand returned to Cairhien through the Gateway (after first encountering that Seanchan patrol), it was approximately two hours before dawn (according to Asmo).

The only way Rand and Avi could have seen the sunrise at point A, Travel, and then see it rise again in 2 hours at point B, is if point B (Cairhien) was ~2,000 miles west of point A (Seanchan). But, that's not the case.

So, either RJ made a mistake when describing the sunrise timing in the two places, in that sceen. Or, Avi's Gateway to Seanchan opened into the past or future. But, RJ was asked once if the timing of that scene was deliberately calculated on his part, taking into account time zones, and RJ said yes, he knew exactly how far west Seanchan was. Implying that the sun behavior he described in the scene was exactly as he wanted it to be - i.e. NOT an error.

Even if the one assumption above is incorrect, if you look at the map of the whole world in the Guide, there is NO place on Seanchan, in either hemisphere, that could account for only a two hour difference in sunrise time between Seanchan and Cairhien. The only way there could have been a 2hr difference in sunrise time is if Rand and Avi had been at a longitude about 2 hrs east of Cairhien - i.e. in the Aiel Waste.

I don't like the idea of time travel Gateways, but I'm at a loss to find another explanation, given the info above.