Complex sentence: Although the Canucks lost that game 4--1, Neilson's actions inadvertently began quite a trend as, when the teams returned to Vancouver for the next game, many fans brought white towels to the game and began waving them above their heads.
Split into simpler sentences: Although the Canucks lost that game 4--1, Neilson's actions inadvertently began a Vancouver tradition. When the teams returned to Vancouver for the next game, many fans brought white towels to the game and began waving them above their heads.