The 26-year-old allowed a tame free kick to drift in at the far post as Rangers lost more ground on second place against Dundee.
Jak Alnwick was brought to Ibrox side Glasgow Rangers in January, after representing Newcastle United earlier in his career.
Rangers brought in three new faces during the January transfer window.
Rangers goalkeeper Jak Alnwick has been praised by Steve Harper.
The former Port Vale goalkeeper may be thrust into the action after Wes Foderingham's mistake against Hearts.
The talented goalkeeper arrived from Port Vale on Monday as he looks to challenge for the number one position at Rangers.
Celtic goalkeeper Leo Fasan replaces Rangers' new boy Jak Alnwick at Port Vale.
Newcastle supporters were less than convinced about Rangers new boy Jak Alnwick.
Rangers have snapped up goalkeeper Jak Alnwick today.
The 23-year-old is reportedly set to join Rangers from Port Vale after failing to make the grade at Newcastle United.