Skyline

While the film Skyline might have taken its share of brickbats, few could criticise the quantity and quality of extras that come with this DVD release. Fraternal directors Greg and Colin Strause give one full audio commentary, while co-writer/producer Liam O'Donnell and co-writer/animation supervisor/second unit director Joshua Cordes give another, and all four provide additional (optional) commentaries on the assorted deleted and alternate scenes, as well as on the two trailers. Their enthusiasm for the project is infectious, perhaps best summarised by one of the writers, who declares the 11 months that it took from script to completion to be "the best year of our lives – you get to work with all your best friends every day."

The directors' commentary is a master class on how to get the most out of a relatively small budget: film in your own condo (with minimal set dressing) and in real locations, use whatever vehicles you have to hand ("we didn't rent"), use simple in-camera effects whenever possible, and shoot lots of empty spaces and cityscapes which can be filled with VFX in postproduction. Meanwhile, using a Red digital camera enabled them to reduce the cost of lighting, and to shoot the film's many aerial shots in a single day.

The brothers also explain how the original three-day span of the alien invasion ("a giant FU to humanity") was reduced to two, and document some of the concepts and visuals which had to be changed because of problems with the MPAA, and talk through the beats – many more subtle than a first viewing might suggest – of their protagonist Jarrod's transformation. They concede that their characters' survival of a nearby nuclear blast is the first bit of the film that is "not realistic", while adding (not unreasonably, given the genre in which they are operating), "You've gotta have a little bit of movie magic somewhere." Finally, Colin observes drily, "I seem to hate pregnant women – I'm not quite sure why."

Writers O'Donnell and Cordes offer a hilariously geeky perspective on their input into the "Romero alien invasion movie", happily citing their influences ("we went Revenge Of the Sith on that shot", "that was the Michael Bay shot", "anybody who doesn't like Starship Troopers is a fool!", etc), and Cordes can barely contain his excitement at having been able to include the Wilhelm scream in the sound mix of one sequence.

They champion the film's dark tone, pointing out that only in an independent production like theirs is it possible to "make humanity lose". Finally, they talk through the development of the film's coda, set inside the mothership – a sequence which was not in the original screenplay, but of which they wholeheartedly approve for its purely visual storytelling and for its setting up of a (presumably very different) sequel. "It's not always the best on the page", they conclude – although it is also rare for a film's writers to have played such an active role throughout the production.

The deleted, extended and alternate scenes all comprise further character drama, mostly cut for reasons of narrative economy, but interesting enough nonetheless – especially those scenes concerning the protagonist's work as a painter. Two 'pre-vis' animation sequences show just how close the finished product was to what had been planned, even if, as one of the commentators puts it: "There's plenty of crap we made up on the spot." In discussing the trailer, all four commentators emphasise how much they would have preferred the image of the helicopter being grabbed by tentacles to have been kept out of the public eye – but they admit that it will no doubt have helped put their film on the horizon.