Trek's been terrible at depicting space battles. In what ways have you noticed their being wrong, or right? Nevermind budgetary concerns and tired apologetics. Forget space-fantasy -- this is a science-fiction question.
- The positions of ships are usually way too close to one another.
- Ships should maneuver differently in space than in water/atmosphere (no banking to turn).
- Ships/armadas can appear to just sit there instead of dizzying the eye with constant future-y movement.
- Weapons don't appear to be nearly as destructive as they should -- judging by the explosions and their effect on unshielded targets.
- Explosions don't look like they should in outer space.
- Different weapons techs of different aliens should appear/explode differently.
- Weapons travel too slowly (phasers should at light speed and torpedoes at FTL).
- Weapons miss too often or are not smart enough to retarget and try again.
- Weapons don't fire often enough.
- Weapons don't fire from enough weapons ports.
- There should be far more varieties of ship present -- especially if they reuse ships from a century prior.
- We should be seeing more exhaust from impulse engines and thrusters, especially during extreme combat situations.
- We should see more distortion in atmosphere from wind, clouds, heat, and sonic boom.