Is that a result of thin-film interference? Several years ago, I was laying on my bed and had a CD shaped transparent plastic disk (which was covering a 100 CD stack), basically a transparent CD. I don't know why but I took my phone and took a picture of the light bulb in my room through the hole of that plastic disk. Here is the result:

Why does it appear like that? does it have anything to do with Thin-film interference? And would it look the same if there was no hole in the middle?
 A: You are looking through a CD? (with lots of grooves).  I believe what you made is a transmission diffraction grating. 
A: Judging by the smoothness and regularity of the spectrum, this appears to be simple refraction through the plastic. Thin-film interference would generate a much less regular pattern. In this instance, the plastic disk is acting as a sort of prism.
If you want a thin-film interference type of effect, you can look at the disk (from either side, if I recall correctly) and bend it just slightly; the internal stresses in the disk material will cause the light to reflect and refract in ways that vary with the stresses. It's still not technically thin-film interference, but the principles at play are similar.
A: How about a simple test to see if the rings are due to thin film interference?  I doubt it, as that implies very high quality manufacturing, with precise rings of very uniform and varying thicknesses, but a test is easy.  Try using monochromatic light.  Even just the green (or red) 'charging' LED light on a phone/laptop charger should change the pattern if it is due to interference. An LED power/charging indicator with more than one color is even better.  Red should show a different pattern than yellow or green if they are due to interference.  Do NOT use a pointer laser.  Do NOT use any powerful laser, led or other.
