Modern audiences are apt to notice the presence of matte lines. Reviewer Glenn Erickson said that "the ambitious special effects were some of the first to garner jeers for their lack of realism". Erickson correctly assesses the film as "a flop that seriously hindered George Pal's career as a producer". Paul Brenner said, "Pal pulls out all stops in the special effects department, creating 'The Wheel', rocket launches into space, and a breathtaking near collision with an asteroid". "The Encyclopedia of Science Fiction" said "The special effects are quite ambitious but clumsily executed, in particular the matte work". Paul Corupe said that often "the overall image on screen that inspires awe: the Martian landscape, the general's high-tech office, and the vastness of the cosmos. The film's budget is certainly up on screen for your entertainment, but it's just spectacle for spectacle's sake". He, too, complains of matte lines, but acknowledges, "the composites are convincing enough for the time the film was made". Corupe described it as the "first big flop in Pal's career. It was a major setback that saw him abandon science fiction filmmaking for five years, including a planned sequel to "When Worlds Collide"" "The Encyclopedia of Science Fiction" remarks "A truly awful film, "Conquest of Space" is probably George Pal's worst production".