Five things we learned from the FA Cup and Premier League this weekend

Don't witter on about timekeeping without checking your watch

Arsène Wenger was furious that the referee, Andre Marriner, who took charge of their game against Liverpool, signalled eight minutes of stoppage time but played nearly 12, giving the visitors time not only to concede a penalty in the seventh minute, but to score one of their own in the last. "We conceded a penalty after 11 minutes and the extra time was only eight minutes," he said. "I don't know where this additional time came from."

If he's seen the game again, or read this morning's Sun, he should know by now. The tabloid examines the period in forensic detail: one minute and three seconds elapsed between Liverpool conceding the penalty and Arsenal scoring it, and Van Persie's celebration – for which he was booked – lasted a further 46 seconds.

Clearly, though, Dirk Kuyt was expecting the worst when he launched an optimistic shot direct from the subsequent kick-off. But those delays gave Liverpool enough time to win a free-kick on the edge of Arsenal's penalty area, which was awarded after 8mins 45sec of stoppage time. Mainly because of the time Arsenal took to retreat 10 yards, it took a full two minutes before Luis Suárez took his shot. Five seconds after that Lucas Leiva tumbled under Emmanuel Eboué's challenge and another penalty was awarded. In all, The Sun calculated that just 4mins 49secs of actual football was played between the end of the 90th minute and the final whistle.

According to Fifa's Law 7, which covers the duration of a match, "the announcement of the additional time does not indicate the exact amount of time left in the match. The time may be increased if the referee considers it appropriate but never reduced."

It's understandable if Wenger is flabbergasted that his side found yet another novel way of not winning a match, but this is one whinge too many.

A season can change in a second

It was all about stoppage time in London this weekend. At Upton Park on Saturday, as the 90th minute came to an end with the scoreline between West Ham and Aston Villa still resolutely stuck at 1-1, the visitors were 15th in the league and still haunted by the grisly spectre of relegation, despite employing most of the England squad. Forty-four seconds later Gabriel Agbonlahor headed in Ashley Young's cross and they were in the top half of the table, having leapt six places in a stroke.

If Villa's form continues in their next three, winnable games – against Stoke, West Bromwich and Wigan – they might recall with rheumy nostalgia the distant days (actually just a couple of weeks earlier) when they actually worried about relegation. How quickly a team's fortunes can change.

Wigan have opened a window of opportunity

After being crunked 4-0 on the opening day at home by newly promoted Blackpool, Wigan fans must have felt it was going to be a long season. The Latics have spent 19 weeks in the bottom three – Blackpool, until now, none. Of the three Ws facing the drop, Roberto Martínez's side looked the surest shot – Wolves have played better than their position suggests; West Ham will come good.

But revenge is worth waiting for; revenge you can stick in the deep freeze and allow to harden. It needed a bit of luck, and Blackpool were the most generous of hosts (see below), but Wigan are off the bottom, where they've sat since the start of March, and out of the relegation places. Their top two scorers, Hugo Rodallega and Charles N'Zogbia, netted for the first time in more than two months ... and their next opponents? Tailspin team Sunderland, whom Wigan have beaten five times in nine previous Premier League encounters.

No one is calling which teams will go down this season (the closest Alan Hansen would come to a prediction on Match of the Day was "three from the bottom five") but Wigan have thrown themselves a lifeline. Perhaps more importantly, they've done Premier League survival for a few years now. The road to Wigan's salvation may just have started at the town with three piers.

Diabolical defending makes for divine comedy

You select your variant of 4-2-3-1. You drill your players in how to hold their shape when the opposition has the ball. You tirelessly work on getting that zonal marking system right ... And then your centre-back passes to the opposition directly from a free-kick, then falls over while trying to get back and cover. Or your goalkeeper fails to collect a ball being shepherded back to him by a team-mate. Or your holding midfielder, known for the range and accuracy of his passing, gives away possession on the edge of your box with your defence in disarray. It's no wonder managers tend to be a testy bunch.

Winning a football match is often about outwitting your opponent, gaining a tactical edge, springing a surprise from the bench. But success just as frequently comes down to being less inept, less often. Never mind inverting the other guy's pyramid, he'll demolish it himself if you wait long enough. Getting on for half of the goals scored in the six Premier League and two FA Cup matches resulted directly from errors that schoolboys would have been embarrassed to commit. Ashley Young botching Villa's offside trap; Paul Robinson's misplaced pass teeing up Matthew Etherington; Scott Carson failing to … well, all right, we knew what to expect there.

Bloopers are, of course, among the game's richer lowbrow pleasures (see also: fighting and penalty shoot-outs), so in many ways it was a vintage weekend. Golden goals may win awards but it's own goals and gaffs that sell videos.

Scholes looks about ready to take his leave

"I'll decide at the end of the season. I really don't know what I am going to do yet ... People always say you should play as long as you can but there comes a time when you can't physically do it. I'm wary of that." So said Paul Scholes, when discussing the prospect of his retirement with Daniel Taylor last week. Scholes's lazy late lunge on Pablo Zabaleta, and the resigned look with which he received his marching orders at Wembley, certainly betrayed a touch of weltschmerz – a sense of frustration that his legs can no longer quite manage what his mind demands. And if that is Scholes's last significant action on a football pitch, a Zidane-esque full stop, some will see it as appropriate for a player prone to what Sir Alex Ferguson referred to after the game as "red-mist moments". But, well, we all prefer to remember the good times, don't we?