Yes, Aliens are on board Prometheus
At least three aliens have been spotted on the set of Ridley Scott’s long-awaited Prometheus film.
"Though security on the set is very tight with the good weather, dock doors have been open and cast and crew have been enjoying lunch outdoors. I can confirm seeing three aliens having lunch. Not the whole costume but blueish costumes and the unmistakable heads hanging around their shoulders," an unnamed source told AlienPrequelNews.
"The alien heads were the same shape but no markings, only a plane bronze color. As for the suits black boots and shoulder pads the rest was a Chelsea blue body suit could be for SFX, all the sets around the back of the bond stage have huge green chromokey maybe that's a clue. I have witnessed foam cut outs of unmistakable aliens all cut in half lengthwise so they could be in the floor walls - and very much from the original film."
If true, the report seems to confirm that Prometheus will contain elements of an Alien prequel, despite Scott’s (somewhat confusing) statement about the movie being a "jumping-off point" with its own "grand mythology and universe."
To be sure, Prometheus is expected to follow Weyland Industries before its merger with the Yutani Corporation, while exploring the nature and origins of the enigmatic extraterrestrial pilot briefly featured in the original Alien film.
During a previous interview, Scott hinted the films would be about "gods and […] engineers of space," intimating that the Xenomorph Alien was designed either as a biological weapon or as a means to "clean up" planets.
It should be noted that actor Michael Fassbender recently emphasized the link between Prometheus and Alien, when he said: "Prometheus is absolutely connected to Alien... There's a definite connecting vein."