The files that save to the goggles are 1 file for the entire flight while the files saved on the flight unit are broken up into separate files with max size 3.51 Gig.  Is this normal? Can it be changed?

The goggles files will be broken if you fly long enough.
Yes, this is normal. No it can't be changed.
It's something to do with file system. It's pretty common on lots of camera.

Hello there. Good day and thank you for the inquiry. The maximum capacity of a single file will not exceed 4GB. If exceeded, the recording will be stopped, and a new recording will be started. In addition, the maximum file size of FAT32 is 4GB. Hence, a file that is larger than or equal to 4GB will be divided, otherwise, the file may be lost or abnormal and cannot be read. Although exFAT allows a larger file size, the larger file may be damaged due to abnormal power-off and SD card removal, or even cannot be recovered. So the storage of the camera is 4GB regardless of the file systems. So it is normal the video will be split if it reaches 4GB. Thank you and fly safe always.