diff --git a/programs/instant-send-program/src/instructions/initialize_transfer.rs b/programs/instant-send-program/src/instructions/initialize_transfer.rs
index 21b599a..37362a2 100644
--- a/programs/instant-send-program/src/instructions/initialize_transfer.rs
+++ b/programs/instant-send-program/src/instructions/initialize_transfer.rs
@@ -44,6 +44,7 @@ impl<'info> InitializeTransferSPL<'info> {
         CpiContext::new(self.token_program.to_account_info(), cpi_accounts)
     }
 
+    // REVIEW: should be claim_rent_from_sender
     pub fn cliam_rent_from_sender(&self) -> Result<()> {
         let rent = Rent::get()?;
         let recipient_token_account_rent = rent.minimum_balance(TokenAccount::LEN);
diff --git a/programs/instant-send-program/src/instructions/redeem_funds.rs b/programs/instant-send-program/src/instructions/redeem_funds.rs
index bce1115..69b5c68 100644
--- a/programs/instant-send-program/src/instructions/redeem_funds.rs
+++ b/programs/instant-send-program/src/instructions/redeem_funds.rs
@@ -126,6 +126,7 @@ pub struct RedeemFundsSOL<'info> {
 }
 
 impl<'info> RedeemFundsSOL<'info> {
+    // REVIEW: I assume the secret is randomly generated, otherwise it would be better to use a hash and a salt
     pub fn verify_secret(&self, secret: &str) -> Result<()> {
         let provided_hash = {
             let mut hasher = Sha256::new();
@@ -140,6 +141,7 @@ impl<'info> RedeemFundsSOL<'info> {
     }
 
     pub fn transfer_sol_to_recipient(&self, amount: u64) -> Result<()> {
+        // REVIEW: you have to use the system program to transfer lamports, like you did in the initialize_transfer_spl instruction
         **self.recipient.to_account_info().try_borrow_mut_lamports()? += amount;
         **self.escrow_account.to_account_info().try_borrow_mut_lamports()? -= amount;
         Ok(())
@@ -166,6 +168,7 @@ pub fn redeem_funds_sol(ctx: Context<RedeemFundsSOL>, secret: String) -> Result<
 
     ctx.accounts.escrow_account.is_redeemed = true;
     ctx.accounts.transfer_sol_to_recipient(ctx.accounts.escrow_account.amount)?;
+    // REVIEW: after the transfer, the escrow account should be deleted
     // ctx.accounts.refund_remaining_lamports_to_sender()?;
 
     Ok(())
diff --git a/programs/instant-send-program/src/instructions/refund_funds.rs b/programs/instant-send-program/src/instructions/refund_funds.rs
index 28f0d35..da0dbd0 100644
--- a/programs/instant-send-program/src/instructions/refund_funds.rs
+++ b/programs/instant-send-program/src/instructions/refund_funds.rs
@@ -31,6 +31,7 @@ pub struct RefundFundsSPL<'info> {
 }
 
 impl<'info> RefundFundsSPL<'info> {
+    // REVIEW: I assume the secret is randomly generated, otherwise it would be better to use a hash and a salt
     pub fn verify_secret(&self, secret: &str) -> Result<()> {
         let provided_hash = {
             let mut hasher = Sha256::new();
@@ -122,6 +123,7 @@ impl<'info> RefundFundsSOL<'info> {
     }
 
     pub fn transfer_sol_back_to_sender(&self, amount: u64) -> Result<()> {
+        // REVIEW: this also does not work because you need to call the system program to transfer lamports
         **self.sender.to_account_info().try_borrow_mut_lamports()? += amount;
         **self
             .escrow_account