They stunk in and forced him at gunpoint to do what we saw him do at the opening of the previous episode.
Another interpretation could be that he saw one of them and went down to let them in.
I didn’t see anyone in the car pointing a gun at him. He drove off alone, unless someone was hiding in the backseat or something but it sounds pretty lame. The Garbage Goths like to wait, and don’t seem the type to pull off what they supposedly did.
We couldn’t see any gun, but there was someone in the back seat as he drove off. A persons shadow rose out of the back seat as he drove away. We can only assume it was one of the new group.
Okay. I rewatched that scene and didn’t see anyone pop up. Maybe I’ll have to adjust the brightness. If it happened, then if makes sense.
We saw someone sit up, but believed it to be the passenger seat.
Dull episode, I agree the change in the isolated group’s behaviour and language was unrealistic, but the one thing I did like was the Kingdom warrioress at the beginning commenting on the Walker’s maxi dress repeatedly. Yeah, her, your sister, and most of the female extras had that dress 
They weren’t exactly in the best emotional state, but if Carol and Daryl aren’t going to do it when they’re alone in a house in the middle of the woods, after an emotional reunion, next to the cozy fireplace, they’re not ever going to do it.
Do what? 
This thread is rated for Mature Audiences.
Acting? 
There was a loud commotion shortly after Gabe entered the storeroom. I assume that is where he was surprised and taken prisoner/hostage.
The Trash Collectors seem to be a pretty stealthy bunch (which I’m sure will prove useful against the Saviors later on). Gabe stumbled into the raiding party. At least they chose not to kill Gabe, which is good thing, but he did seem to be treated as a prisoner at the junk yard.
Why did he leave the watch post?
He is damned goofy as does stuff like that, but why?
Maybe that’s the established pattern for an Alexandria watch? Maybe Gabe didn’t follow the normal pattern, which would be why he stumbled in to the raiders? Maybe it’s because the writers wanted Gabe to be captured so they could write in clues which would eventually lead Rick’s group to the junk yard inhabitants?
Poetic license.
I found it weird that no one seemed greatly concerned by how fucked up Rick’s hand was after his confrontation with the shiny walker. That would get badly infected in a place like that.
I muttered something about antibiotics, and Mrs. Plant (v.3.0) muttered something in agreement.
I do think that the saviors (sp)? took all their meds, did they not?
What did Gabriel steal, three cans of pork & beans and one can of tomato soup?
They are arguing about that?
He stole every bit of food they had. Everything. Did you no see him filling several large containers with food an the shelves completely empty afterwards?
I think the new group is called the Scavengers, but I like Garbage Goths better. 
I’ve been calling them the Junkers, pending an official name.
Not the Junkies because heroin would be long gone out of that world.