When they track down the hostages the men realise Dillon hasn't been entirely honest and they're not the first unit sent in. The real trouble comes when they go to leave they encounter something entirely unexpected and it starts hunting them.
CW: off colour jokes and language you wouldn't do now but aren't mean-spirited
John McTiernan's debut feature has aged very well.
Arnie had by this point become a passable actor for these kind of roles and he's surrounded by a well chosen supporting cast whose characters each have a schtick. The only oddity is Elpidia Carrillo as the enemy captive who's just there with little to do but get dragged around. Given the year and genre you'd expect her to be a victim or love interest but she just delivers a little low impact exposition which is in some ways good and others disappointing. It's notable though that very quickly the badasses start to listen to her and there's an excellent moment where Dutch frees her, going against the grain of "commies bad m'kay".
Most people remember the set piece showdown where Arnie is painted with mud, but the enormous majority of the movie is the whole main cast doing the soldiers in the jungle under threat thing and this is very nicely tense. There is even a bit of decent narrative to what the team are doing there in the first place. A lazier film would have just painted them as heroes but Dutch and his team have been given a shit illegal job to do and they know it. It doesn't subvert the macho action movie cliches at all but it uses them knowingly. In a movie that exists purely so Arnie can have a fight with a 7' tall alien in the jungle nobody would have noticed at the time if the pretext was shit but now that attention to detail means this stands the test of time. No it's not serious cinema but you can see everybody involved gave a shit about making the whole thing stand up to scrutiny, not just the action.
The creature makeup still looks good today, only the hands have that "rubber suit" look and the invisibility effect and thermal vision antagonist perspective are iconic.
One of the great action movies of the 80s, 9/10, yes really.
This launched a long-lived franchise from nothing that has taken fewer missteps than most. Everybody gave their all with it being a significant step up from Commando etc. and it shows. It still works as solid entertainment getting on for 40 years later.