Corrected entry: When Glenn goes to see what is left in an old gun store with Meggie and Tara he finds 3 gun silencer. Silencers are illegal in all of America so it would be highly unlikely for an actual gun store to contain silencers. (01:00:00)
Corrected entry: When Rick closes the gate he realises that walkers could have got in, so he starts to run down the street in daylight. The scene changes then goes back to Rick - he's still running but it's pitch black.
Correction: There's no error and it's done to show passage of time. As you said, the scene changes. In fact it changes twice, once with the preacher and then the group meeting, before it goes back to Rick. Even though Rick is still running, he's in a completely different part of the town, as opposed to seeing him still run near the gate.
Correction: Silencers are legal to purchase (under certain restrictions) in most of the USA: https://silencerco.com/education/.