I don't think it's a huge problem, but it isn't great marketing. In this case it's partly about the specific product, but also about the brand.
It is true that the brand of production tools often doesn't match the brand advertised. When this discrepancy is not visible to your audience, there's no problem. Allowing your audience to see the discrepancy, IMO, subtly undermines your own brand, plus you've used your own money to say something positive about your competitor's product and brand. The G2 is a fun camera to run around with, but the pros who shot this used Canon. I don't see any positive spin there, and marketing is all about the spin.
I watched a promo video being made for Windows 7, interviews with Win7 users, shots of them using Win7, etc. Every computer used by the production staff was a Mac. There were no Macs visible in the final piece, and I very much doubt anybody in Microsoft marketing would have allowed release of a "Making of..." video showing the Macs in use.