Corrected entry: When Paul forms the plutonium into a ball, he slips it into one end of a transfer pipe, and uses a magnet on a chain to retrieve it from the other end. However, it should be noted that plutonium is NOT magnetic.
Corrected entry: Paul Stevens breaks into the secret lab to steal some plutonium. After procuring a small container full of the material, he then cuts a small hole through the building's wall with a huge laser. He straps the plutonium to a radio controlled toy car and puts it through the hole. After getting himself out of the building by another route, he then drives the toy car through a drain pipe to re-acquire it. But why go to all that trouble with the laser, etc.? He had to walk out of the lab somehow. Why not just carry the plutonium out with him? The reason, of course, is that the laser looked pretty cool on screen.
Corrected entry: A neutron-emitting "initiator" is needed to set off a nuclear bomb, but there is use (or even mention) of such in the movie.
Corrected entry: Very early in the film, the percent purity of the processed Plutonium is shown being ranked on a graph by mass in atomic mass units. Much later that same measurement is shown being graphed in terms of alpha emission energy.
Corrected entry: Paul Stevens finds an anomalously large number of mutant five leaf clovers on the lawn outside the secret weapons laboratory, which is presented as evidence of the large quantity of highly radioactive plutonium within. If the radiation were leaking out in large enough amounts to cause that many mutations in the plant life, then surely everyone both inside and immediately outside would be as good as dead.
Corrected entry: In the last few minutes of the film the kid's homemade nuclear implosion bomb is stuck with the timer ticking away toward zero, at which it'll explode and destroy everything within a radius of several miles. Everyone in the lab is frantically trying to figure out how to disarm the bomb without setting it off in the process. In fact, all they have to do is find some crude way to smash the device, ruining the spherical symmetry of the jacket of conventional chemical high explosive surrounding the smaller sphere of fissile plutonium. By destroying the spherical symmetry of the implosion, the nuclear chain reaction will not proceed efficiently. Thus, even if the timer sets off the device, only the comparatively harmless chemical explosive will detonate.