Partick Thistle 1 - 1 Hearts: Controversial goal earns Hearts draw
The Jambos keeper allowed a weak shot from Thistle’s Blair Spittle to creep through his body and it looked certain to secure a first win of the season for the hosts.
However, Callachan was on target for the second game in succession with 10 minutes to go to retain Craig Levein’s unbeaten record since taking charge.
Despite their disappointing opening to the season, Thistle have showed signs lately of finding their feet, and they started the game confidently.
Spittal and Miles Storey combined nicely on halfway, before the former went on a driving run and shot narrowly wide of the far post from 20 yards.
The two continued to provide a threat, dropping off into awkward positions for the Hearts back three, but it was Ryan Scully who was called into action first as the keeper pulled off a good low save to deny Michael Smith at the other end.
The hosts took the lead in the 18th minute and it was Spittal who was on target, cutting in from the right before shooting.
The effort was weak and straight at McLaughlin, but the keeper somehow let it through his hands and legs before it dribbled over the line.
Hearts were firmly on the back foot and struggling to cope with the Jags’ midfield, and were thankful for the intervention of John Souttar, who headed off the line to prevent Paul McGinn’s glancing header sneaking in.
Jamie Walker almost levelled the scores seven minutes into the second half after a fine turn and shot from 25 yards, but his effort drifted wide with Scully beaten before Isma Goncalves missed with a similar attempt.
The hosts retreated deeper and deeper but still restricted the Jambos to long-distance efforts, though Connor Randall stung the fingertips of Scully with a rasping effort from 25 yards.
However, after a sustained period of pressure, Hearts finally levelled with 10 minutes to go as Callachan thumped a header back across goal and over the line.
A covering Thistle defender thought he had got to it in time to clear, but referee Don Robertson awarded the goal to the delight of the visiting fans.
Storey had a final effort saved by McLaughlin before volleying over late on as Alan Archibald’s side were forced to accept another draw.