A few things don't make sense to me. Assuming these things haven't been done.
1.) Why didn't they immediately stash away some guns and matchup the inventory? I'm sure Rick sat everyone in the town down and talked about Negan and the new way they would be doing things. They already knew he would come at some point to get some supplies. Unless he came the very next morning, why didn't he stash away some guns? Its not like they had much else to do during the day.
2.) Why is Rick so scared? I've seen this group with their hands tied with guns to their heads,in the middle of a cannibal outpost tied up,surrounded by bikers,or at war with the Governor. In comparison, Neegan presents a lighter threat than what they have faced before. I can see Rick bowing down right after Abraham and Glen were killed and they had guns to their heads, but I don't get how he is just rolling over like this when they got back. Unless he was waiting for Carol and Morgan to come back first.