Another interpretation of "And it came to pass after the seven days" (Genesis 7:10): that during those seven days the Holy One, blessed be He, altered for them the orders of Creation, so that the sun would rise in the west and set in the east.
The Sun Rose in the West During the Flood Week
Yalkut Shimoni on Torah 56:2
דָּבָר אַחֵר, וַיְהִי לְשִׁבְעַת הַיָּמִים, שֶׁשִּׁינָה עֲלֵיהֶן הַקָּדוֹשׁ בָּרוּךְ הוּא סִדְרֵי בְּרֵאשִׁית שֶׁהָיְתָה חַמָּה יוֹצְאָה מִמַּעֲרָב וְשׁוֹקַעַת בַּמִּזְרָח.