Gillingham took just 30 seconds to open the scoring as Hudson-Odoi linked up with Abdullei down the left to set up Andy Pugh who fired the visitors in front from the edge of the area.
The home side should have equalised soon after as Djilali's low cross carried to Comley at the far post but the Eagles captain blazed over the bar from close range.
Djilali laid on an almost identical cross in the 18th minute, this time Pinney was guilty of spurning a guilt edged chance at the far post.
Midway through the half Nick Carle had a well struck shot blocked by Richards whilst at the other end Yussuff's free kick wasn't far off target after McCammon was brought down en route to goal
Shortly before half time Gillingham nearly struck again as McCammon climbed above the home defence to meet Yussuff's free-kick from the left only to see his effort drop over the crossbar.
On the stroke of half time a Palace corner was half cleared to the lively Djilali but the winger's half volley flashed wide of Julian's left hand upright.
HT 0-1
Palace went desperately close again direct from the re-start, Djilali the provider from the right, Comley placing his finish the wrong side of the post.
In the 51st minute Ryan Smith's excellent run took him one on one with Alan Julian, the keeper took the sting out of his neat chip and Tom Brunt arrived to avert the danger with a fine sliding clearance.
Moments later Smith found space on the left to send over a teasing cross Brunt attempted to clear the danger only to slice on to his own post before Gillingham cleared upfield.
On the hour mark, Mark Robson was surprisingly sent to the stands, or at least the other side of the railing for protesting a challenge on Mark McCammon.
The Eagles enjoyed the better of the second half action creating plenty of openings but somehow contriving to miss the target. Then five minutes from full time Jack Holland rose to meet Smith's corner and powered into the net to tie the scores.
The late goal enthused Palace's youngsters who went for the win in the final minutes, Comley going close with a cheeky 40 yard effort that had Julian back-pedaling to make the save.
Gillingham: Alan Julian, Alex Brown, Ryan Benniman, Tom Brunt, Garry Richards, Rashid Yussuff, Andy Pugh, Adam Miller, Amoudou Abdullei (Trialist 72), Mark McCammon, Bradley Hudson-Odoi (Sam Fisher 90)
Subs not used: Daran Hawkes, George Humber
Crystal Palace: Lloyd Anderson, Michael Abnett, Matthew Parsons, Jack Holland, Jerry Nnamani, James Comley, Kieran Djilali, Nick Carle, Nathaniel Pinney, Kieron Cadogan, Ryan Smith.
Subs not used: Charlie Holness, Jack Randall, Ibra Sekejja, Hakeem Adelakun, Joe Goldsmith.