Which of the following is NOT a typical error leading to overexposed radiographic film?

The correct answer is that applying the fixer before the developer is not a typical error that leads to overexposed radiographic film. This is because the purpose of the developer is to reduce the exposed silver halide crystals in the film, allowing the latent image to be formed. If the fixer is applied before the developer, it halts the development process prematurely, resulting in an underdeveloped image rather than an overexposed one.

For the other options, leaving the collimator open allows for a larger area of the film to be exposed to radiation, thus increasing the overall exposure and potentially leading to overexposure. If the film is exposed to light, it can cause fogging or excessive exposure in the areas that were light-struck, contributing to an overexposed appearance. A developer temperature that is too high can increase the activity level of the developer, causing the film to develop more rapidly and leading to overexposure. Each of these factors directly relates to achieving an overexposed film due to excessive radiation exposure or increased processing activity.