Probably a sample/early run game. Some features similar to the one I am just finishing a restore on. See my thread https://pinside.com/pinball/forum/topic/star-trek-tng-next-chapter

Domed cannons were on the early games although of course many newer games have been changed to domed cannons.
I see a few other differences from later production games. The chromed metal wire form on the front of the apron does not go all the way to the left (It does on most games) There should be a piece of clear plastic all the way to the left on your game.
On the bottom of the playfield the board attached in a vertical fashion in front of the 2 VUKs (the opto board) is in a different position from standard production games. Some of the wiring also follows different paths.

bottom wiring 3.jpg

The gray rubber switch covers were also omitted on later games.

Stuart