When you encounter a bug in offline play or a situation where the AI missed an obvious play, please follow this procedure for submitting the save game file to us. It is best if you don't play past the position in the game where the event occurred.
On Windows, the save files are stored in your AppData directory. If you navigate to your home directory, you should see the AppData directory. It you don't see it, it is hidden by your file system. You can add AppData to the path in the address bar in Windows Explorer to get into it. From there, our save files in AppData\LocalLow\Playdek\Twilight Struggle.
On Mac, the save files are stored under your home directory in ~/Library/Application Support/unity.Playdek.Twilight Struggle. Library might be hidden on your system, but you can use "Go/Go to Folder..." from the Finder menu to enter the path manually.
Go ahead and zip up everything in the save directory and email it to firstname.lastname@example.org so we can take a look at it.