Like most of his teammates, McCallan is a part-timer player who holds down a full-time job -in his case as a PE teacher in Belfast.
With Ireland heading unexpectedly into the second round Super Eights, which last from March 27 to April 21, after their shock three-wicket win over Pakistan, McCallan will need special permission to remain in the Caribbean.
"Personally I'm due to go back on April 1 and will have to ring the headmistress and ask her to give me another few weeks off," McCallan said.
"But it's great prestige for the school where I work and for the rest of the employers. It's a massive thing for Irish cricket so let's take it further."
McCallan, who is Trent Johnston's vice-captain, believes Ireland can continue to cause shockwaves on their World Cup debut with host nation West Indies next in their sights in their final Group D match at Sabina Park here on Friday.
"We're not satisfied with what we've done so far, we're looking to take more scalps now," 31-year-old McCallan told the BBC.
"I'll be honest and say we did think we could do this. Coach Adrian Birrell has instilled a sense of belief that we're capable of creating an upset."
The win was also the perfect reply to the critics who say that non-Test playing nations, such as Ireland, have no place at the World Cup which has already seen three of the heaviest defeats in tournament history occur here.
Ireland now have three points in their group after tying their opener with Zimbabwe.
"People are entitled to their opinion but we believe we're good enough to be here and it's imperative to our cricket to have something to aspire to," added McCallan.
"It would be a sorry day when cricket was restricted to nine or 10 teams and hopefully we've done our bit to push the associate cause.
"I know there have been some big defeats (Ireland lost four matches at the World Cricket League in Kenya in the run-up to the World Cup) but against Pakistan, one of the big Test teams, we've proved we're capable of beating anybody."