"Fifa rules apparently state that teams must name three goalkeepers in their squad for the World Cup," writes Joe Diaz. "Has anyone ever used all three, or is it just a complete waste of a squad number?"

Article 26.3 of Fifa's World Cup Regulations (a thrilling read if you have the time) indeed states: "Each association will be required to provide Fifa with a final [squad] list of no more than 23 players (three of whom shall be goalkeepers)." The convention of naming three keepers in a squad goes back to 1934 (the United States had named only one in their squad in 1930). Several teams changed goalkeepers mid-tournament in the early years but you have go all the way to 1974 to find the first substitute goalkeeper, when Mwamba Kazadi of Zaire conceded three goals in the first 20 minutes and was replaced by Tubilandu Dimbi (who went on to concede another six).

The need to use several goalkeepers is rare – in 1990 the 24 teams used a total of 27 keepers, while as recently as 1998 the 32 sides in France used a combined 36. In all, only four teams have ever used three goalkeepers in a single World Cup tournament. That's out of 371 teams to have qualified for the finals – surely time for Fifa to change the rules.

First to use a trio of keepers were France in 1978. The No1 was Jean-Paul Bertrand-Demanes who played in Les Bleus' opening game against Italy. In the second group game against Argentina, Bertrand-Demanes smashed either his back or head (it varies between reports) on a post after pulling off a save and had to be replaced by Dominique Baratelli, a 31-year-old who had made sporadic appearances since 1969. He conceded the winning goal against Argentina and was replaced for France's final group game by Dominique Dropsy. The game against Hungary was Dropsy's debut and he would go on to win another 16 caps. Neither Baratelli nor Bertrand-Demanes would ever play for the national side again.

Belgium went into the 1982 tournament with the eccentric (he served a three-month ban in 1980 after elbowing a linesman in a Belgian Cup match) but hugely talented Jean-Marie Pfaff as their first choice. Pfaff had been welcomed, somewhat apprehensively, back to the fold after missing the 1978 European Championships because of his practical joking, but he couldn't keep his inner comedian under wraps. He was dropped following the first group stage after apparently pretending to drown in the swimming pool at the team hotel. His replacement in Belgium's opening game in the second group stage was Theo Custers, whose performance against Poland was so abject it was his last ("Custers's last stand," notes the World Cup historian Cris Freddi). For the Belgian's final game Jacky Munaron took the gloves.

Also in 1982, Czechoslovakia used three keepers. Zdenek Hruska played from start to finish against Kuwait, but Stanislav Seman was preferred for the Czech's game against England. A calamitous performance – it would be his last for the national side – lasted 75 minutes before he broke a finger and was replaced by third-choice Karel Stromsik, who kept the No1 spot for the final group game.

The most recent team to use three goalkeepers in a single tournament were the hapless Greece side of 1994. The Greeks had gone undefeated through qualifying and named the experienced Antonis Minou, who had conceded only twice in five qualifiers, as No1 for the opening game against Argentina. A 4-0 defeat saw 25-year-old AEK keeper Elias Atmatsidis in goal against Bulgaria. Another 4-0 defeat followed and he was replaced by 24-year-old Christos Karkamanis for the final group game. That brought a slight improvement in fortunes – a 2-0 defeat to Nigeria.

OPPOSING BROTHERS

"Kevin-Prince Boateng has opted to play for his father's country of Ghana, while his brother Jérôme, has opted to play for his own country of birth, Germany," writes Lee Richardson. "With both teams drawn together in the same group this World Cup, and both players looking likely to be selected for their relevant squads, there is a good possibility of two brothers playing against each other in an international. Has this ever happened before?"

As several readers have pointed out, the only previous occasion on record of two brothers facing each other in an international (and not even a full international at that) was in February 2008 when Marseille goalkeeper Steve Mandanda lined up in goal for France A against a Democratic Republic of the Congo side that had his brother Parfair in goal. Steve seems to have been substituted at half-time, while Parfait came on for the second half.

"Interestingly Steve was actually born in the Congolese capital Kinshasa, while Parfait was born in Nevers, France," notes Phil Walsh.

UNATTACHED PLAYERS AT THE WORLD CUP

"According to Fifa's official squad lists Australia's Craig Moore doesn't have a club and nor do two New Zealand players," writes Sam Allan. "Would they be the first unattached players to appear at a World Cup?"

No is the short answer. The long answer, if you're the Knowledge inbox this week is: Gary Breen, Gary Breen, Gary Breen, Gary Breen, Gary Breen, Gary Breen, Gary Breen, Gary Breen, Gary Breen. The centre-half was between clubs at the 2002 World Cup, his contract with Coventry City having expired. He joined West Ham after the tournament.

More interestingly, writes Quinten Taylor, Canada's squad in the 1986 World Cup had six unattached players – Bruce Wilson, the brilliantly named Randy Ragan, Randy Samuel, Greg Ion, Jamie Lowery and Sven Habermann – due to the demise of the NASL in 1985 where most had plied their trade. The story of their qualification and their efforts in Mexico can be found here and here.

The United States have a history of taking players without clubs to World Cups. "In the 1990 two players travelled to Italy while still playing college soccer in the US," writes Evan Garcia in Santa Monica, California. "Chris Henderson, who was at UCLA, where he won a national championship in 1990, and went on to earn 79 caps although did not play in Italy, and midfielder Neil Covone from Wake Forest University." And, as Joe Tiernan and Jack Cunha point out, the bulk of the US squad in 1994 was centrally contracted to US Soccer and therefore unaffiliated to any club.

Angola's No1 at the 2006 tournament João Ricardo had been released by Portuguese club Moreirense in 2005 and kept his fitness by training alone. His Angola captain Akwa was in the same boat, having been released by Qatari side Al-Wakra.

It's not really in the spirit of the question but Zinedine Zidane in 2006, Jürgen Klinsmann in 1998 and Michael Laudrup in the same year were to retire after the tournament and had technically left their respective clubs, Fred Sullivan, Stephen Savva and Benjamin Bilde Boelsmand point out. Boelsmand adds that Diego Maradona was without a club in 1994 (he had played his last game for Newell's Old Boys in December 1993).

Pat Jennings retired from first-team club football in 1985, but was in the Northern Ireland squad for the 1986 tournament, writes Phil Kayes, while Tony Cascarino was between Chelsea and Marseille while with Ireland in 1994 according to Kevin O'Brien.

A couple of unique cases to finish. "Pat Bonner was released by Lou Macari after the last game of the 1993-94 season," writes Danny O'Donnell. "But during the summer Macari was dismissed by the new Celtic owner Fergus McCann and replaced by the Kilmarnock manager Tommy Burns. Following his release from Celtic, if rumours were to be believed, Bonner was likely to join Burns at Kilmarnock. However, Tommy's move to Celtic saw Bonner return to the club for the start of the 1994-95 season. Bonner, though, was not contracted during the 1994 tournament."

And this from Mick Reynolds: "Jose Luis Brown – the World Cup-winning defender for Argentina who was released from his club Deportivo Espanol prior to the 1986 tournament. Subsequently went on to score in the final against West Germany."

KNOWLEDGE WORLD CUP ARCHIVE

"Is it true that Chilean players drank vodka during the 1962 World Cup because they thought it would help their chances of beating the USSR?" asked Steven Davison back in the summer of 2006.

Incredibly, Steven, it is. During the group stage, the hosts employed an interesting new tactic of pre-game stereotypical eating: before the opening 3-1 win over Switzerland, they ate cheese, followed by a preparatory meal of spaghetti before the 2-0 success against Italy.

Once in the quarter-finals, the Chileans prepared for their game with the mighty Union of Soviet Socialist Republics by downing a couple of Smirnoffs. The ploy actually worked and Chile went on to win 2-1. Coffee was the order of the day before the semi-final with Brazil, but although it perked them up no end in the morning, it couldn't stop the Brazilians from winning 4-2 and going on to lift the trophy. Eduardo Galeano wrote in Soccer in Sun and Shadow that Chile "gobbled down spaghetti, chocolate, and vodka, but choked on the coffee".

For thousands more questions and answers take a trip through the Knowledge archive.

Can you help?

"After the preliminary World Cup squads were announced last week I noticed that none of the teams who qualified for Euro 2008 can potentially name the same squad of 23 at this tournament as they did two years ago," writes Jim McNulty. "So, has any country ever actually managed to do this?"

"Saarland competed as a team in the qualifying rounds for the 1954 World Cup," writes Graham Clayton. "Have there been any other examples of non-national teams competing in the qualifying rounds of the World Cup?"

"While trawling through the World Cup posters from this weeks Joy of Six, I noticed that the 66 World Cup was played significantly later in the summer than the other finals," writes Jeremy Nash. "Any idea why? Were they having problems relaying the Wembley pitch?"

"With rumours that David James is hoping to become manager of Portsmouth, and given that he has been selected for Fabio Capello's World Cup squad, would this be the first time a club manager has played in a World Cup finals?" wonders Rich Liddiatt.

"Who has commentated on the most World Cup games in history?" writes Jim Arras. "And how many times have they done it?"

Send your World Cup questions and answers to knowledge@theguardian.com