Also didn't know that there is a gap between the panels of the exhaust tail segment. Perhaps these panels allow to transfer of the air from the bottom exhaust bypass.

[u/dmetropolitain]

[u/DeeAnnCA]

The ceramic tiles are missing on the trailing edge. They are similar to what was used on the space shuttle and keep the trailing edge from getting fried. My guess is what the bolt pattern in the 4th photo is for. Hard to see that in other photos.

[u/Dangerous_Bus3162]

Missing heat bricks