No it's ridiculous.
Firstly the ability to notice details which are absolutely irrelevant to the real task in hand is not a useful skill nor is blindly following instructions even if they appear ridiculous.
It is also probably putting off good candidates as it suggests a petty and pedantic management style, remember that an interview goes both ways if this is the best thing you can come up with to evaluate candidates it suggest that you have very little knowledge about the skills required.
You also say that you are looking for serious candidates, putting a deliberate trap in an application suggest the opposite of that.
There is also the consideration that job applications are a chore for everybody involved and there is a very good reason why the format of the process is as standardised as possible. The reality is that professional applicants are going to want to be able to send a standard CV and a covering letter which actually addresses their suitability for the job. Presumably you want to attract people who are in demand and don't feel like they have to jump through hoops to stand a chance.
If you want to recruit good people than giving applicants the impression that you are doing them a massive favour by even interviewing them isn't going to help.
