Meditation side effects Recently I tried to meditate in a moving car. I started seeing shadow like houses or roads with close eyes. It was followed by intense pain in eyes, nausea and dizziness. The headaches and nausea went away once I stopped meditating in the car. 
I have also reduced my practice from one hour to 20 minutes. One hour of meditation was giving me lots of benefits as I was more present throughout the day.
Now I have come to know about the side effects of meditation and advanced stages like “dark night of the soul” and different psychological illnesses like depersonalisation caused by meditation. 
My question is that can an average person who is meditating for half hour or an hour a day get these side effects?
My question is that can an average person who is meditating for half hour or an hour a day get these side effects? 

Assuming you are doing Vipassana.
Yes, any-type of experience is possible with a meditator.
It doesn't depend upon, "whether meditation is done for 1/2 - 1 hour or by seemingly average person" rather it depends upon , "how dedicatively meditation is practiced?".  

You just started in car, for I started in a Bus later-on in a train. I started from 10s to 100s to 1000s of kms. journey.  

Yes, symptoms remained same at start. 

These were till I stopped having belly-full food during journey or before journey. Sometimes I would complete my journey by remaining hungry for 1000s of kms. and dedicatively focusing on meditation by taking adhitthana(it means to fixate your posture irrespective of room/place is shaking or not). This way, concentration increased, even the continuous noise of bus tyre or train helped me to focus on breath, sensations, seeing thoughts and analysing different sankharas through their body-effect.  

Moreover, it was during journey till now, that I have made any progress in meditation.
It's just a start, don't flee away from it. Meditation is not always about merely getting calmness within 1/2 - 1 hr. It takes a lot to really calm and rectify your previous/current bad-habbits.