I've made a walkthrough video about it.
1. The shells mysterously became 4/4 after getting 4 from an enemy, whereas I previously had more than 20.
2. Interacting with the dog outside the gas station gives me two options (1) pet donut (2) pet buddy. And when I chose 1, it saves the game. Don't know if this is a word bug.
3. I can kill the BOSS when I didn't trigger the dialogue "what the f--". It escaped to the last room, but ran out again. Had to fight it again.