OCAS (Canada) interview questions

The old adage if something sounds too good to be true, it usually is, applies here. The interviewers were pie in the sky, everything is sunshine and roses and is the best place to work this side of the sun! Of course this got me actually excited about the job and my experience matched up to what they seemed to be looking for. They made me feel like I had absolutely nailed the interview. I was told the process would take a couple of weeks to complete. Not less than 48 hrs I got a note saying thank you but you are not a good fit. I was dumbfounded because I was completely in sync with the interviewers. And how could another person get their references checked, an offer made, and accepted in less than 48 hrs from my interview even if we assume I was the last one. So something seems very much off to me. It's not about not getting the position or getting rejected but that it very much seemed they had a candidate in mind, perhaps internally which is a waste of time for externals