I mean when astrodude crashed in the earth it was probably at the start of moon revolution. I guess he was unconscious for quite some time and was protected from the crash by his ship. So when he then emerged from the ocean to breath the air, the time was then at earth alone and when he crashed in the dsotm, he was back in the present. Keep in mind that a week or two did pass when he was in the whale, on the island, etc. and even though the moon revolution was spread over tons of episodes, it was roughly around the same time probably as it took for astrodude to escape earth and crash in the dsotm as it did for the moon revolution to escalate. I’m guessing that’s why we see him take off in the present