Ofcom said Sky had made "an error of judgement" and that the programme contravened rule 10.1 of the broadcasting code, which demands that broadcasters retain editorial control over programme content.
The regulator argued that in a number of camera shots, branded towels draped around players' shoulders appeared to have been deliberately arranged to display the Gillette logo as clearly as possible.
Gillette is a sponsor of the England rugby team. However, Ofcom has ruled that branded rugby shirts and other appearances of the brand were acceptable.
Ofcom also upheld ITV for beer brand Cobra's sponsorship of a screening of family film Mary Poppins on ITV3. It said the credits, which showed a bottle of Cobra beer twice within each bumper and the address of the brand's website, were unsuitable for a film likely to attract a large audience of under-18s.