Two words that commonly get mixed up are allude and elude. Both words have totally different meanings, and therefore if used incorrectly changes the meaning of your sentence.
Allude – To make a disguised reference to something. This means that you talk about a problem without actually mentioning the problem.
For example: in a paper you may mention how researching for a topic was incredibly difficult which alluded to the fact that information was sparse to non-existent.
Elude – means to escape either mentally or physically.
For example: The thief eluded the police by escaping down an alley.