Since gliders don't have engines, is it possible for them to go around? Are there any extra features on a glider to try to prevent that situation from happening?
No. A (pure) glider cannot make a go-around in the way a powered machine can. The glide path can be influenced by airbrakes, flaps, chutes or slipping, but mostly those are for reducing your L/D, i.e. steepening the approach (you win again, gravity!).
Gaining height without updraft is only possible by converting kinetic energy (speed), and that gain is limited by the stall speed. So while you can get up a few meters by pulling up from landing airspeed, you will find yourself way too high above the runway at minimum speed and hoping for the best.
The highly enjoyable* spectacle of a low fly-by of a glider is achieved by starting with really high (unlandable) speed which is then converted into height and shortly followed by the inevitable landing**. For some older (mostly wooden) gliders, even this is not a very good idea because they combine a lower VNE with lower L/D ratios, leaving you low and slow after pulling up from redline speeds.
In a glider, you get one chance for a smooth landing (freak thermals excluding). But this is one of the most important points in training, and you get used to the concept very quickly. A proper landing procedure together with brakes, flaps, etc. will bring you down safely.
*but not necessarily safe or recommended
** lest you catch a proper thermal or dynamic updraft.
No, a glider can't make a go around, but if they are going fast enough they can make a low pass (which looks like a go around), but that generally means that they won't be in a position to actually land even if they wanted to. The key to safely managing and landing a glider is energy management. When coming in to land it can't be too slow and low OR too high and fast (only one factor can be adjusted by trading altitude for airspeed or vice-versa).
Most gliders have airbrakes or spoilers which are used to bleed off excess energy. A typical approach will have them deployed about half way when on final to land so that they can be used like a throttle in an airplane. If they get low or slow, the airbrakes can be stowed in order to increase the glide ratio (just like adding power in an airplane). If they get high or fast the airbrakes can be extended further and/or the glider can be slipped in order to decrease the glide ratio (just like reducing power in an airplane).
Other than the very high glide ratio and no engine to go around with, they land very similar too an airplane. If you've never flown one, I would highly recommend it. Not only is it fun, it will make you a better overall pilot!
Yes,there is one scenario when they can. At our club we are on the top of a hill and if the ridge is working you can abort the approach close the airbrakes and run over the threshold onto the ridge. In fact our low cable break briefing is land straight ahead or takeoff.
Here's a forced example:
In 2006, I asked a CFIG what he would do if the rope release failed for both the glider and the emergency release on the tow plane.
He suggested we try the exercise of seeing what it would take to land on tow. (It turns out, it is REALLY easy to overrun the tow plane when on descent).
So, technically, I have 3 glider touch-and-goes logged in my logbook.