JavaScript, 432 418

(function x(s){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(i=s.split(m=v='');~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:x+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})(prompt())

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(;~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

I made a version with a less complete version of the song in 344:

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottles of beer ',d='on the wall',e='take one down, pass it around',f=', ';for(;n;)v+=[n,b,d,f,n,b,f,e,f,--n||'no more',b,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[n++];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

JavaScript (ES6), 385

s=>{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(i=s.split(m=v='');~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?99:n,b,n-1?o:m,j,d,'! '].join(m);return s.match(/[^HQ9\+]/,r='')?'Source code contains invalid characters':[...s].map(c=>({H:'Hello World!',9:v,Q:s})[c]).join``}

JavaScript, 344

I made a version with a less complete version of the song:

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottles of beer ',d='on the wall',e='take one down, pass it around',f=', ';for(;n;)v+=[n,b,d,f,n,b,f,e,f,--n||'no more',b,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[n++];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

JavaScript, 432 418

(function x(s){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(i=s.split(m=v='');~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:x+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})(prompt())

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(;~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

Didn't opt for the case-insensitive, would have cost too many characters. Not even close to some of the other entries, but was fun nonetheless!

I made a version with a less complete version of the song in 344:

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottles of beer ',d='on the wall',e='take one down, pass it around',f=', ';for(;n;)v+=[n,b,d,f,n,b,f,e,f,--n||'no more',b,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[n++];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

but after seeing the other entries (and looking at the actual lyrics, who knew!), I thought it was a bit of a cop out!

JavaScript, 432 418

(function x(s){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(i=s.split(m=v='');~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:x+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})(prompt())

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(;~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

Didn't opt for the case-insensitive, would have cost too many characters. Not even close to some of the other entries, but was fun nonetheless!

I made a version with a less complete version of the song in 344:

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottles of beer ',d='on the wall',e='take one down, pass it around',f=', ';for(;n;)v+=[n,b,d,f,n,b,f,e,f,--n||'no more',b,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[n++];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

but after seeing the other entries (and looking at the actual lyrics, who knew!), I thought it was a bit of a cop out!

JavaScript, 432

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(;~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

Didn't opt for the case-insensitive, would have cost too many characters. Not even close to some of the other entries, but was fun nonetheless!

I made a version with a less complete version of the song in 344:

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottles of beer ',d='on the wall',e='take one down, pass it around',f=', ';for(;n;)v+=[n,b,d,f,n,b,f,e,f,--n||'no more',b,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[n++];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

but after seeing the other entries (and looking at the actual lyrics, who knew!), I thought it was a bit of a cop out!

JavaScript, 432 418

(function x(s){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(i=s.split(m=v='');~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:x+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})(prompt())

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottle',j=' of beer',d=' on the wall',e='Take one down, pass it around',k='Go to the store, buy some more',l='No',o='s',f=', ';for(;~n;)v+=[n||l,b,n-1?o:m,j,d,f,n||l,b,n-1?o:m,j,f,n?e:k,f,--n<1?l:n,b,n-1?o:m,j,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[++n];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

Didn't opt for the case-insensitive, would have cost too many characters. Not even close to some of the other entries, but was fun nonetheless!

I made a version with a less complete version of the song in 344:

(function(i){if(s.match(/[^HQ9\+]/)){m='Source code contains invalid characters'}else{n=99,b=' bottles of beer ',d='on the wall',e='take one down, pass it around',f=', ';for(;n;)v+=[n,b,d,f,n,b,f,e,f,--n||'no more',b,d,'! '].join(m);h={H:'Hello World!',Q:arguments.callee+m,9:v};for(;c=i[n++];)m+=h[c]||''}alert(m)})((s=prompt()).split(m=v=''))

but after seeing the other entries (and looking at the actual lyrics, who knew!), I thought it was a bit of a cop out!