A couple of bits:
The +5V for the pots should come from the Arduino 5V output - there are two possible problems with a separate power supply:
The measured value can drift, as the input is no longer ratiometric.
The Arduino inputs may be powered through the pots, causing damage.
Also, in two places you have the possibility of connecting a pot wiper to +5V. If that ever happens at a low setting on the pot, it's shorting the 5V to ground and also likely burn up the pot track.
Use the changeover switch to disconnect the wiper when it connects to power, or switch the pot ground to +5V, or add a series resistor (1K) between the pot wiper and its cap to eliminate the short possibility.
Also, I notice you have a 9V battery holder in there;
7V is the absolute minimum for a 7805 input.
A 9V can and will drop to 6V in use - use a low dropout regulator instead of the 7805, otherwise you will be endlessly discarding good batteries.
I don't really see anything that calls for a separate 5V supply? I'd just use the Nano 5V output and get rid of the separate regulator, it will simplify things and save power. It's rated for around 500mA and you should not need a fee tens of mA for the pots etc.