In a D&D 5e session I'm planning, my party of ~4 1st level characters is going to investigate an abandoned outpost that was taken over by goblins. Naturally, the goblins are keeping an eye on the surroundings, and when the party reaches a certain distance away from the outpost, a nearby rock will lift up like a trapdoor and a small handful of goblin guards will climb out of a tight tunnel underneath and order the party to follow them. They'll be taken to the outpost and positioned at the base of its tower, where the boss of the goblin warband stands to speak with them. If the party makes the boss angry, he will trigger a net trap to spring up from where they are standing to immobilize them, whereupon they'll be taken to the outpost's basement and locked in a cell.

Now, if the party is being stealthy before the initial group of goblins finds them, they might not even get spotted at all and can continue to the outpost unhindered. An early perception check at the rock could reveal that it doesn't look in place and may have been moved. They have the opportunity to fight off the goblins, though the number of them makes this a risky-looking option. If they've already been taken to the tower, a perception check could reveal that they're standing on a trap as they talk with the boss. And if the trap is triggered, a dexterity save (with a lower DC if they noticed the trap beforehand) will let them get out of the way before it's fully sprung. Party members that separated from the captured and/or trapped group have the opportunity to go back to town for backup, or continue sneaking around if applicable. And the group that does end up getting thrown in the cell will have opportunities to break out, though I haven't written them yet.

Despite having all these additional conditions, this encounter doesn't sit well with me. Is there anything else I can do to make it feel more fair?