I just started up the Cavalcade short on the disc 3 DVD, and the Shadowrama is below the bottom of my teevee screen. I can see the very top of one of their riffer’s heads, but that’s it. It seems like the size of the total video is too big.
I am willing to accept if this is just due to the fact that I have a stupidly old teevee, but is this an issue for anyone else?
ETA: This is the only thing so far that has had this issue. Everything else has been properly sized.
I don’t have the DVDs to test, but I can confirm that the “Cavalcade” short on Blu-ray looks proper. Any chance you maybe sat on the remote and/or accidentally pressed a “zoom” button on it? I’ve been known to do that.
If not, could be other things: If it’s a really old player, it might be confused with something in the MPEG encoding, details that tell the player how to size and format the image. MPEG-2 is a pretty old standard and people should know better than to tinker with it when mastering because it can break compatibility with old players, but it has happened.
Less likely is a mastering error, which means everyone’s DVD is like that. 
If the TV itself is really old, and you’re using a connection like composite or component, maybe there’s some sort of digital-to-analog conversion weirdness going on? Speaking as an engineer, have you considered giving either device a good whack?
Given that nobody else has seen this issue, I’m thinking there is something in this short that my ancient setup doesn’t like (DVD player is 14-ish years old, teevee is 20+ years old). When I watch it on the DVD, then I can just pretend it is a Rifftrax, since I can’t see any shadows.