Centre James Glover was helped from the field after just three minutes and midway through the first half captain and prop Matt James departed on a stretcher before being taken to hospital by ambulance for treatment to a dislocated ankle.
Sheffield responded to the second setback almost immediately, Thackeray sending Joel Farrell over for a try which Pat Walker converted.
That levelled the scores following Jarrad Stack’s opener, created and improved by Jamie Dallimore who landed a long-range penalty just before the interval to send Barrow in 8-6 ahead.
The combination responsible for Eagles’ opening try struck again, Farrell crossing from another Thackeray pass.
Ben Blackmore went in off a fine pass by Josh Guzdek, then Thackeray bagged a brace, stepping through the defence from close-range, then finishing off a move which began in Eagles’ half. Walker maintained his 100 per cent kicking record.
In a bad-tempered finale, Thackeray was sin-binned for dissent and Barrow took advantage of their extra man to add tries by Theerapol Ritson and Jonathan Smith, Dallimore converting the first.
Sheffield Eagles: Guzdek, Miller, Glover, Hellewell, Blackmore, P Walker, Thackeray, Moran, Burns, James, Davies, Farrell, Brown. Substitutes: Makelim, Mason, Esslemont, Tagg.
Barrow: Ritson, Cross, Stack, Amean, Spedding, Dallimore, Charnock, Johnson, Puara, Susino, Walne, Smith, Aspinwall. Substitutes: T Walker, Mossop, Toal, Riley.
Referee: M Mannifield (Huddersfield).