This one is a much bigger problem since it is generally accepted as a the scientific method. It is my main reason for hating on the science community. The original author/inventor of the method Ockham declared himself that this method should be used for theologic explanations not for scientific ones.

Big Bang Theory

One of the first offenders that comes to mind. The Big Bang Theory is rooted in a very simplistic argument, the universe is expanding, therefore if you travel back in time it is shrinking until it reaches critical mass. Since then a lot of Theory has been based on the existence of a big bang, cosmic radiance being the noise of the Big Bang ie. The problem is that once you expand on a theory that you accepted on insufficient criteria it is hard to get rid of it. It is like re-doing the foundation of a house after you completed the roof.

Evolution Theory

The survival of the fittest as a sole drive for evolution has been debunked a long time. It is often hard to impossible to prove a theory, however it is simple to disprove it. Scientists found switches on our DNA that are influenced by extreme situations. In case of low nutrition/starvation these switches will trigger and children of those people will be smaller. There is no doubt about some sort of Evolution of life taking place, but the simple explanation by Darwin has been proved to be wrong and it was only accepted for such a long time because it was simple.

Mathematic vs Science

Once again there is a language barrier. In Germany we refer to Chemistry, Physics and Biology as Sciences of Nature (Naturwissenschaften). Mathematics is science, yes, but it is not a science of nature. It is a constructional science and therefore actually closer to Law/Juristic then to Biology. Scientists have always been fascinated by the mathematic concept of a proof and therefore they like to include as much math/numbers as possible to make their theories sound more true.

Science (of Nature) tries to describe nature and since we are limited in our perception we will never be able to fully grasp our environment. Therefore all Science of Nature can never be true. An example for a known to be wrong model that is teached to us is the Bohr model. The Bohr model is still usable as a rule of thumb, but it fails in too many scenarios to be regarded as true.

Mathematics never claims to describe reality and can therefore be true. If you put 5 cats in a box every day you will not have 35 at the end of the weak, at least not if you don't provide them with water and food. Math does not care about reality, it is a completely made up constructed science.

Partly based on: https://de.wikipedia.org/wiki/Ockhams_Rasiermesser