At least two egregiously bad offside calls were made this morning, one of which influenced a major cup tournament outcome. Since it appears FIFA referees (and, in one case, soccer broadcasters) don't understand this basic rule, we're going to illustrate them.
The above clip is from today's Spurs-Sunderland match. While at first glance it appears to, indeed, be offside (Sunderland's keeper is the guy in yellow) the rule only applies in the attacking half of the field. Thus, the Tottenham goal should have counted. Perhaps it is even more surprising that the international feed announcers are unsure about how the rule is interpreted.
A less complicated but even worse example, here, from today's Africa Cup Of Nations match between Equatorial Guinea and Congo. This one took what should have been an Equatorial Guinea win and turned it into a 1-1 draw:
This is a really neat goal that was ruined by a blown offside call. There's no confusion over the rules here, just a blind (or, uh, corrupt) assistant referee. (For what it's worth, Equatorial Guinea—the victims in this blown call—is the host nation and one of the most corrupt countries on Earth.)
Missed offside calls happen all the time in soccer, and are likely to continue as long as human beings are tasked with monitoring it. But it's not too much to ask that the officials at least understand the rule.