I agree it is a plot hole,but it will be patched up in the 9th episode when he is able to send a message to April and it seems the turtles meet Shredder for the first time in that episode. As for the summaries of the episodes. Its what Ii get off of tv.com and wikipedia.org, mainly the former. I plan on editing the "tentative" summary after the episodes air.
Please,everyone PM to help me add to the first post with episode titles, episode writers,and notes about the episodes i. e. the Baxter debut being the first footage shown and the first Shredder encounter sharing the episode title of the second episode of the orginial cartoon and other notes like that to add.