There are a number of crew cameos in the film. The gas-masked figures were regularly played by members of the crew, including Mark Maltby, Thomas Shawcroft, Ciaran Maginn, Charles Shawcroft and Trudy Pye. The gas-masked figure that strikes down Shannon in the long-grass was played by Director Harrison Wall.
There are a number of dystopian references in Weaverfish, hinting at the existence of a larger back story than what is directly depicted on screen. The fictional town in which the film is set is called Huxley Wells, combining the surnames of science fiction authors Aldous Huxley and HG Wells. The fictional location, Fountainhead Creek, is also named after Ayn Rand's "The Fountainhead". In Weaverfish, the company supplying the barrels of biological solvents is named Aquatopia.
The wide shots of the perimeter fence were created in visual effects. However, the close ups, in which the characters interact with the fence, were filmed using a budget piece of mesh fence from a garden center. This involved having two crew members stood up to their waists in water holding the fence from off screen.